Bicycle gear shifting system

ABSTRACT

A bicycle front shifting system includes operable to transmit a wireless signal, a crank assembly with two crank arms and a pedal on each of the two crank arms. The crank assembly is rotatable about a rotation axis. A front shift unit is coupled to the crank assembly and is rotatable about the rotation axis. The front shift unit includes a chain ring component with a big chain ring and a small chain ring. The small chain ring has a small diameter and the big chain ring has a big diameter that is larger than the small diameter. A shift mechanism is coupled to and rotatable with the chain ring component about the rotation axis. The shift mechanism is configured to receive the wireless signal from the shifter and to shift a chain between the big chain ring and the small chain ring according to the wireless signal.

RELATED APPLICATION DATA

This patent is related to and claims priority benefit of prior filed U.Sprovisional application Ser. No. 62/754,312, filed Nov. 1, 2018 and U.S.provisional application Ser. No. 62/801,085, filed Feb. 4, 2019. Theentire contents of these prior filed applications are herebyincorporated herein by reference.

BACKGROUND 1. Field of the Disclosure

The present disclosure is generally directed to front shifting systemsfor bicycles, and more particularly to a front shifting system that isincorporated as a part of a crank assembly of a bicycle.

2. Description of Related Art

A bicycle typically includes a system for driving a chain on a bicycleto provide motive force for the system. A driving system typicallyinvolves a front and a rear drive.

Rear cassette and front chain ring shifting systems for bicycles areknown in the art. Such shifting systems typically utilize a front orrear derailleur to move the chain from one sprocket or chain ring toanother. The typical front or rear derailleur is mounted to a stationarypart of a frame of a bicycle. A rear derailleur is typically mounted toor directly adjacent to the rear wheel dropouts on the bicycle frame.Thus, the frame is often provided with a bracket at the dropout locationfor attaching the rear derailleur.

Traditional front drive systems include a crank assembly. The crankassembly may include two crank arms connected by a spindle. The crankassembly may also include one or more driving sprockets. When two ormore driving sprockets are used various techniques for shifting thechain from one driving sprocket to another driving sprocket have beenused.

The most common technique involves the use of a front gear changingdevice, such as a front derailleur typically mounted to a frame of abicycle, the includes plates positioned on either side of the chain topush the chain between driving sprockets. The front derailleur istypically mounted to the seat tube or other part of a bicycle frame thatis closely adjacent the front chain rings of the crank assembly. Anopen, accessible location must then be left on the seat tube frame toaccommodate clamping a front derailleur to the tube. In some cases, amounting bracket is provided on the bicycle frame for attaching thefront derailleur to the frame. The pushing technique of frontderailleurs can cause rough drive transitions between driving sprockets,and can be problematic when shifting under load.

Existing front derailleurs can create several other problems,disadvantages, or drawbacks for the bicycle, including the framedesigner. For example, the frame designer must account for a mountinglocation for the front derailleur when designing the frame of a bicyclewith a front shifting system. Thus, a portion of the frame must be leftaccessible and positioned relatively close to the front chain rings.Having to accommodate for mounting a front derailleur to a part of thebicycle frame places design constraints on the designer. It is possiblethat, when mounting the front derailleur to the bicycle frame, thederailleur is incorrectly positioned relative to the front chain rings.This can reduce the quality and effectiveness of a front shiftingoperation or can result in the inability to shift, particularly when thechain is under heavy loads.

Also, mounting the front derailleur to a portion of the bicycle frameeffectively makes the frame a part of the front shifting system. While abicycle is being ridden, the frame can flex when under stress. Anymovement or flexing of the frame where the front derailleur is mountedor between that mounting location and the attachment point of the frontchain rings can cause shifting problems. For example, a rider mayattempt to execute a shift operation while the frame is flexed,resulting in misalignment of the front derailleur and the front chainrings. Such misalignment can again result in poor shift quality, causethe chain to derail, or allow the chain to slip during the shift. Suchmisalignment may again result in the inability to execute a shift,particularly under heavy chain loads.

The known front derailleur designs also can make installation andbicycle set-up more difficult, and thus more time consuming and/orexpensive. The installer must take the steps necessary to separatelyobtain the clamps or fasteners, the necessary tools, and the derailleurand then install the front derailleur on the bicycle frame. Theinstaller, or another person tuning or setting up the bicycle, must thenalso properly position and align the front derailleur relative to thefront chain rings during set-up of the system. The set-up can bedifficult to do for those lacking specific skills and training. Properpositioning and alignment of the front derailleur relative to the frontchain rings is required to ensure quality shifting capability.

SUMMARY

In an example a bicycle front shifting assembly is presented. The frontshifting assembly includes a front shift unit configured to be coupledto a crank assembly for rotation therewith about a rotation axis, thefront shift unit having a chain ring component and a shift mechanismcoupled to the chain ring component. The chain ring component has a bigchain ring having a plurality of teeth defining a big chainring planeand a small chain ring having a plurality of teeth defining a smallchainring plane, the small chain ring having a small diameter and thebig chain ring having a big diameter that is larger than the smalldiameter. The shift mechanism includes at least one protruding shiftelement disposed in a transition zone between the big chain ring and thesmall chain ring, the shift mechanism configured to move the at leastone protruding shift element axially between the big chainring plane andthe small chainring plane.

In an example, a front shift unit for a bicycle is provided. The frontshift unit includes a chain ring component having a big chain ring and asmall chain ring joined for co-rotation with one another about arotation axis, the big chain ring having a big diameter and a pluralityof big ring sprocket teeth and the small chain ring having a smalldiameter and a plurality of small ring sprocket teeth, the big diameterbeing larger than the small diameter. The front shift unit also includesa shift mechanism coupled to the chain ring component, the shiftmechanism including an electronic control unit, a gearmotor unit, atleast one upshift element, at least one downshift element, and a powersupply arranged to provide power for the electronic control unit and thegearmotor unit to operate the at least one upshift element and the atleast one downshift element. The at least one upshift element isdisposed in a transition zone between the small chain ring teeth and thebig chain ring teeth and axially movable by the electronic control unitand the gearmotor unit to shift a chain from the plurality of small ringsprocket teeth on the small chain ring to the plurality of big ringsprocket teeth on the big chain ring. The at least one downshift elementis operable by the electronic control unit and the gearmotor unit toshift a chain from the plurality of big ring sprocket teeth on the bigchain ring to the plurality of small ring sprocket teeth on the smallchain ring.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects, features, and advantages of the present invention will becomeapparent upon reading the following description in conjunction with thedrawing figures, in which:

FIG. 1 shows a side view of one example of a bicycle in a conventionalroad-ready condition, the bicycle including a front shifting system inaccordance with the teachings of the present disclosure.

FIG. 2 shows a right or outboard side plan view of part of the crankassembly of the bicycle in FIG. 1 and including a substantial portion ofone example of a front shifting system in accordance with the teachingsof the present disclosure.

FIG. 3 shows the crank assembly and the front shifting system of FIG. 2but with the bicycle chain removed.

FIG. 4 shows a right or outboard side perspective view of the crankassembly and front shifting system of FIG. 3 .

FIGS. 5 and 5B show a left or inboard side plan view of the crankassembly and front shifting system of FIG. 3 .

FIG. 6 shows a rear view of the crank assembly and front shifting systemof FIG. 3 .

FIG. 7 shows a perspective view of one example of a bicycle chain, asdepicted in FIGS. 1 and 2 , and suitable for the front shifting systemin accordance with the teachings of the present disclosure.

FIG. 8 shows a top view of the bicycle chain of FIG. 7 .

FIG. 9 shows a side view of the bicycle chain of FIG. 7 .

FIG. 10 shows a right or outboard side plan view of one example of afront shift unit of the front shifting system of FIG. 3 and with acowling and crank arm removed.

FIG. 11 shows a right or outboard side perspective view of the frontshift unit of FIG. 10 and with the shift mechanism components in anupshift state in accordance with the teachings of the presentdisclosure.

FIG. 12 shows the front shift unit of FIG. 11 , but with the shiftmechanism components in a downshift state in accordance with theteachings of the present disclosure.

FIG. 13 shows a cross-section taken along line 13-13 of the front shiftunit of FIG. 10 and with the shift mechanism components in the upshiftstate of FIG. 11 .

FIG. 14 shows a right or outboard side perspective view of one exampleof a chain ring component of the front shift unit of FIG. 10 and withthe shift mechanism components removed.

FIG. 15 shows a right or outboard side plan view of the chain ringcomponent of FIG. 14 .

FIG. 16 shows a rear view of the chain ring component of FIG. 14 .

FIG. 17 shows a top view of one example of an upshift element of theshift mechanism for the front shift unit of FIG. 10 in accordance withthe teachings of the present disclosure.

FIG. 18 shows a left or inboard side view of the upshift element of FIG.17 .

FIG. 19 shows a perspective view of one example of a chain guiding pegof the upshift element of FIG. 17 in accordance with the teachings ofthe present disclosure.

FIG. 20 shows a top view of the chain guiding peg of FIG. 19 .

FIG. 21 shows a left or inboard side view of the chain guiding peg ofFIG. 19 .

FIG. 22 shows a rear view of the chain guiding peg of FIG. 19 .

FIG. 23 shows a perspective view of one example of a chain upshiftingpeg of the upshift element of FIG. 17 in accordance with the teachingsof the present disclosure.

FIG. 24 shows a top view of the chain upshifting peg of FIG. 23 .

FIG. 25 shows a left or inboard side view of the chain upshifting peg ofFIG. 23

FIG. 26 shows a rear view of the chain upshifting peg of FIG. 23 .

FIG. 27 shows a perspective view of one example of a downshift elementof the shift mechanism for the front shift unit of FIG. 10 in accordancewith the teachings of the present disclosure.

FIG. 28 shows a front view of the downshift element of FIG. 27 .

FIG. 29 shows a left or inboard side view of the downshift element ofFIG. 27 .

FIG. 30 shows a perspective view of one example of an upshift driver ofthe shift mechanism for the front shift unit of FIG. 10 in accordancewith the teachings of the present disclosure.

FIG. 31 shows a perspective view of one example of an upshift actuatorof the shift mechanism for the front shift unit of FIG. 10 in accordancewith the teachings of the present disclosure.

FIG. 32 shows a perspective view of one example of a first downshiftdriver of the shift mechanism for the front shift unit of FIG. 10 inaccordance with the teachings of the present disclosure.

FIG. 33 shows a perspective view of one example of a first downshift camof the shift mechanism for the front shift unit of FIG. 10 in accordancewith the teachings of the present disclosure.

FIG. 34 shows a perspective view of one example of a second downshiftdriver of the shift mechanism for the front shift unit of FIG. 10 inaccordance with the teachings of the present disclosure.

FIG. 35 shows a perspective view of one example of a second downshiftcam of the shift mechanism for the front shift unit of FIG. 10 inaccordance with the teachings of the present disclosure.

FIG. 36 shows a left or inboard side perspective view of the chain ringcomponent of FIG. 14 .

FIG. 37 shows a left or inboard side plan view of the chain ringcomponent of FIG. 14 .

FIG. 38 shows a cross-section taken along line 38-38 of the front shiftunit in FIG. 10 and depicting the upshift element of the shift mechanismin the upshift state.

FIG. 39 shows a cross-section taken along line 39-39 of the front shiftunit in FIG. 10 and depicting the first downshift element in the upshiftstate, i.e., a neutral state for the first downshift element.

FIG. 40 shows a cross-section taken along line 40-40 of the front shiftunit of FIG. 10 and depicting the second downshift element in theupshift state, i.e., a neutral state for the second downshift element.

FIG. 41 shows a left or inboard side view of the front shift unit ofFIGS. 10 and 11 , but including the chain, and at the first stage of orjust prior to an upshift operation.

FIG. 42 shows a left or inboard side perspective view of the front shiftunit of FIG. 10 and in the upshift state.

FIG. 43 shows a top view of the front shift unit of FIG. 42 .

FIG. 44 shows the front shift unit of FIG. 42 but in the downshiftstate.

FIG. 45 shows the front shift unit of FIG. 43 but in the downshiftstate.

FIG. 46 shows the cross-section of the front shift unit of FIG. 13 butwith the shift mechanism components in the downshift state.

FIGS. 47-49 show the front shift unit and chain of FIG. 41 but with thechain guiding pegs of the upshift element sequentially further engagedwith the chain and the chain shifting from the small chain ring of thechain ring component.

FIG. 50 shows the front shift unit and chain of FIG. 49 but with thechain upshifting peg of the upshift element engaging the chain and thechain shifted further from the small chain ring.

FIG. 51 shows the front shift unit and chain of FIG. 50 but with thechain beginning to engage the big chain ring.

FIG. 52 shows the front shift unit and chain of FIG. 51 but with thechain shifted completely to the big chain ring.

FIG. 53 shows a cross-section taken along line 53-53 of the leadingchain guiding peg in FIG. 47 beginning to engage the chain.

FIG. 54 shows the leading chain guiding peg of FIG. 53 but fullyengaging the chain.

FIG. 55 shows a cross-section taken along line 55-55 of the chainupshifting peg in FIG. 50 beginning to engage the chain.

FIG. 56 shows the chain upshifting peg of FIG. 55 but fully engaging thechain.

FIG. 57 shows the upshift element of FIG. 38 but in the downshift state,i.e., a neutral state for the upshift element.

FIG. 58 shows the first downshift element in FIG. 39 but in thedownshift state.

FIG. 59 shows the front shift unit and chain of FIG. 52 but with thechain beginning to shift from the big chain ring to the small chainring.

FIG. 60 shows the second downshift element in FIG. 40 but in thedownshift state.

FIG. 61 shows a left or inboard side plan view of an alternate exampleof a crank assembly and front shifting system in accordance with theteachings of the present disclosure.

FIGS. 62-74 show an embodiment of a front shifting system including amechanism support bracket and the elements thereof.

FIG. 75 shows an alternate embodiment of the front shifting system ofFIGS. 62-74 .

FIG. 76 shows an alternate embodiment of the front shifting system ofFIGS. 62-74 .

FIG. 77 shows an alternate embodiment of the front shifting system ofFIGS. 62-74 .

FIG. 78 shows an alternate embodiment of the front shifting system ofFIGS. 62-74 .

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is related to front shifting systems for bicyclesand to bicycles that incorporate such front shifting systems. Thedisclosed front shifting systems and bicycles solve or improve upon theabove-noted and/or other problems and disadvantages with prior knownfront shifting systems and bicycles. The front shifting systemsdisclosed herein is incorporated entirely on the chain ring components,with no part separately attached to the bicycle frame. This providesframe designers with greater freedom of design, since the designers donot have to accommodate a portion of the front shifting system on theframe. The disclosed front shifting systems thus also eliminate thepossibility of incorrectly positioning a portion of the front shiftingsystem relative to the chain rings. The disclosed front shifting systemsalso improve shift performance because, since the bicycle frame is not apart of the front shifting system, any flex in the frame during use doesnot cause any problems while shifting. The disclosed front shiftingsystems can also be installed on bicycle frames that are not designedfor mounting a front gear changer or derailleur. The disclosed frontshifting systems shift smoothly and consistently, even while under heavychain loads. The disclosed front shifting systems are easier to installand set up than a traditional front gear changer or derailleur and donot require specific skills or training. These and other objects,features, and advantages of the disclosed hub assemblies and trainerswill become to those having ordinary skill in the art upon reading thisdisclosure.

Those having ordinary skill in the art should understand that thedrawings and detailed description provided herein are for illustrationonly and do not limit the scope of the inventions or the disclosure. Theappended claims define the scope of the inventions and the disclosure.The detailed description below may use terms such as “first”, “second”,“third”, “top”, “bottom”, “left”, “right”, “front”, “rear”, and/or thelike. Use of such terms is only intended for clarity and often merely todifferentiate among parts and components having the same names. Use ofsuch terms is not intended to limit the scope of the disclosure to aspecific order, arrangement, or orientation of such parts or componentsunless specifically stated herein. Further, such terms may refer tobicycle mechanisms that are conventionally mounted to a bicycle and withthe bicycle oriented and used in a standard manner, unless otherwiseindicated.

Also, multiple embodiments of the disclosed front shifting systems andbicycles may be disclosed and described herein. Each embodiment may havea specific combination of features, parts, components, functions,aspects, or the like. The scope of the disclosure is not intended to belimited solely to those specific combinations. Each of the disclosedfeatures, parts, components, functions, aspects and the like may beemployed independent of one another or in other combinations notspecifically disclosed or described herein.

Exchanging, or shifting, a chain between two or more sprockets may beaccomplished with at least one (“1”) shift element being moved into achainline of a drive system. The shift elements may be protruding shiftelements may move in an axial direction relative to a rotational axis ofthe sprockets. The protruding shift elements may be configured to extendand/or retract in the axial direction for moving into and/or out of thechainline. The at least one moving shift element may be disposedradially between a root circle of a larger sprocket and a tooth tip of asmaller sprocket. The at least one moving shift element may include anarray or plurality of protruding shift elements. The protruding shiftelements of the array may be disposed at different radial distancesrelative to the larger and/or smaller sprockets.

Exchanging, or shifting, a change between two or more sprockets may beaccomplished from a larger sprocket to a smaller sprocket usingdownshifting element, which may be formed as a slide or slanted planarsurface that may be moved into, and/or out of, the chainline at thelarger sprocket to cause the chain to slide or shift towards the smallersprocket.

A device for a cycle drive train may include movable shift elements. Themovable shift elements may be disposed on a chain ring structure. Thedevice for a cycle drive train may include movable down shift elements.The movable down shift elements may include a slanted surface configuredto be moved into a chainline of a large chain ring. The device for acycle drive train may include electronic and/or electrical elementsconfigured to control and/or operate shift elements. The electronicand/or electrical elements may be disposed on a chain ring structure.The electronic and/or electrical elements may include an electric motor,electrical linear actuators, solenoids, or other electrical devicesoperable to cause motion or movement. In an example, the electric motor,or other electrical motive device, is configured to cause movement ofthe shift elements.

Turning now to the drawings, FIG. 1 depicts one example of a bicycle 100with a frame 102, a front wheel 104 coupled to a fork 106 of the frame,and a rear wheel 108 coupled to seat stays 110 and chain stays 112 onthe frame. The wheels 104, 108 support the frame 102 above a surface onwhich the bicycle 100 can travel in a forward direction indicated by thearrow ‘A’. The bicycle 100 has a handlebar assembly 114 that is mountedto a head tube 116 of the frame 102. The bicycle 100 also has a seat 118carried by a seat post 120 received in a seat tube 122 of the frame 102.

The bicycle 100 has a multiple-geared drivetrain 124 that may have oneor both of a front gear changer (described further below as a frontshifting system) and a rear gear changer mounted to the frame 102. Thegear changers may be electromechanical derailleurs, for example,including a rear derailleur 126 and a front shifting system, which isdescribed in detail below. The gear changers can be operable using a oneor more gear shifters 128, which may be mounted to the handlebarassembly 114. The gear shifters 128 may operate the gear changes throughwireless communication, as in the disclosed example, or via a physicalconnection using a mechanical shift cable or hydraulic line (not shown).The drivetrain 124 includes chain rings, also described in detail below,that are driven by a crank assembly 132, which has two crank arms 134and two pedals, respectively 136. The chain rings are connected by achain 138 to a plurality of sprockets on the frame 102 at the rear wheel108. The plurality of sprockets may be identified as a rear cassette 140mounted to the frame 102 coaxial with the rear wheel 108. The bicycle100 as described above, other than the chain rings and the frontshifting system, is known in the art and is shown in FIG. 1 to be amountain bike. Those having ordinary skill in the art should recognizethat the type and style of bicycle may vary from the disclosed example.For example, a road bicycle with drop-style handlebars, along with adrivetrain having road type gearing with a road gear range may be usedinstead of a mountain bike or other bicycle gear range.

In this example, the bicycle 100 includes brake system. The brake systemincludes at least one brake lever 142 that is movably connected to thehandlebar assembly 114. The brake lever 142 is configured to operatecomponents of the braking system of the bicycle 100. In one example, thebrake system can include one or both of a hydraulic or cable actuatedfront brake mechanism 144 coupled to the front wheel 104 via a hydraulicline or mechanical cable 146 and a hydraulic or cable actuated rearbrake mechanism (not shown) coupled to the rear wheel 108 through ahydraulic line or mechanical cable 148. As noted above, the brake systemcan be a hydraulic actuated system or a mechanical actuated system andboth are known in the art.

FIGS. 2 and 3 show substantial portions of a front shifting system ofthe drivetrain 124 of the bicycle 100 constructed in accordance with theteachings of the present disclosure and from the right side of thebicycle. The front shifting system includes a front shift unit 150. Thecrank arms 134 of the crank assembly 132 are carried as part of thefront shift unit 150, around which the chain 138 is routed, as shown inFIG. 2 . FIG. 3 shows the same view of the front shifting system, butwith the chain 138 removed. As described in detail below, the frontshift unit 150 carries all the components of the disclosed frontshifting system, other than the gear shifter 128 or wireless actuator.The wireless gear shifter 128 of the front shifting system is notcarried on the front shift unit 150 since it needs to be in easy reachof a rider of the bicycle 100. The gear shifter 128 may instead bemounted remotely on the handlebar assembly 114 of the bicycle 100, asnoted above.

FIGS. 4-6 show perspective, left side, and edge views of the portions ofthe front shifting system and front shift unit 150 depicted in FIGS. 2and 3 . In this example, the front shift unit 150 has two chain rings152 and 154 that are fixedly connected to and concentric with oneanother in order to rotate together about a rotation axis R of the frontshift unit. The chain rings 152, 154 are rotationally or torsionallyengaged with one of the crank arms 134 through a mutual splinedconnection 156. The crank arm 134 is retained to the front shift unit150 by a plurality of screws 158, which have threads configured toengage threaded holes (not shown) in the crank arm around the splinedconnection 156. The screws 158 and splined connection 156 can vary fromthe example shown and can be replaced by other suitable fastener andconnection configurations. The crank arm 134 may be torsionally engagedwith, and retained to, a conventional spindle (not shown) in a mannerthat is well known in the art. The spindle can be rotatably received byball bearings of a bottom bracket (not shown) carried on the frame 102of the bicycle 100. Thus, the front shift unit 150 may be rotatablerelative to the bottom bracket about the rotation axis R.

FIGS. 7-9 depict several views of a small segment of the chain 138. In atypical construction, the chain 138 can be formed of a plurality ofinner and outer links that are joined together. The inner links areformed by pairs of inner plates 164 that define a narrower tooth space166 between the plates. The outer links are formed by pairs of outerplates 168 that define a wider tooth space 170 between the plates. Theplates 164, 168 and links are joined to one another by rivets or pins172 across the links and the width of the chain 138. The rivets 172 caneach optionally carry a roller 174 disposed between the plates and mayinclude a bushing (not shown) between the rollers and rivets.

The chain 138 can engage either one of the chain rings 152, 154 aroundtheir respective circumferences. The chain ring 152 has a relativelylarge diameter and may be called a big chain ring, as is known in theart. The big chain ring 152 has sprocket teeth 160 spaced apart aroundits perimeter or circumference. The chain ring 154 has a smallerdiameter than the big chain ring 152 and may be called a small chainring, as is known in the art. The small chain ring 154 has sprocketteeth 162 spaced apart around its perimeter or circumference. The chain138 engages either the sprocket teeth 160 of the big chain ring 152 orthe sprocket teeth 162 of the small chain ring 154. The small chain ring154 is positioned inboard or to the left of the big chain ring 152 inthis example. The sprocket teeth 160 of the big chain ring 152 may beconfigured to have alternating narrow teeth 160 n and wide teeth 160 was can be seen in FIGS. 4 and 6 . Likewise, the sprocket teeth 162 ofthe small chain ring 154 may be configured to have alternating narrowteeth 162 n and wide teeth 162 w. Thus, the teeth 160 and 162 around therespective chain rings 152, 154 may alternate between being narrow teeth160 n or 162 n to fit the narrower tooth spaces 166 between the innerplates 164 and wide teeth 160 w or 162 w to substantially fill the widertooth spaces 170 between the outer plates 168 of the chain 138. Bypedaling via the crank arms 134 in a rotational direction P, the frontshift unit 150 and the chain 138 rotate, which drives a rear sprocket ofthe rear cassette 140 to propel the bicycle 100 forward in the directionof the arrow A in FIG. 1 .

Still referring to FIGS. 2-6 , a cover or cowling 180 is fixedlyattached to the outboard or right facing side of the front shift unit150 by screws 182 or other suitable fasteners or methods. The cowling180 is sized to cover a substantial portion of the outboard side of thefront shift unit 150 and shaped, i.e., smooth and rounded or domed, toreduce aerodynamic resistance to the bicycle's forward motion. Thecowling 180 may be structural in nature (as opposed to being primarilyan aerodynamic cover) to add strength and stiffness to the front shiftunit 150. Furthermore, the cowling 180 can be configured to keep roaddebris away from the more sensitive parts of the front shift unit 150and to prevent the rider from accidentally coming into contact withthese sensitive parts.

The main components of the front shifting system on the front shift unit150 are first introduced below. More specific details of each of themain components, various additional sub-components, and ancillarycomponents according to the teachings of the present disclosure are thendescribed below. The function and operation of each of the maincomponents, sub-components, and ancillary components are then described.Lastly, the shifting function and operation of the front shifting systemare also described below. In general, the front shifting system includescomponents configured and arranged to shift the chain 138 between thebig chain ring 152 and the small chain ring 154 according to a rider'sselective operation of the shifter 128. The disclosed front shiftingsystem can upshift the chain 138 from the small chain ring 154 to thebig chain ring 152 and can downshift the chain from the big chain ringto the small chain ring. Upshifts and downshifts are performed smoothlyand quickly by the disclosed front shifting system and are performedwith components that are disposed entirely on the front shift unit 150.

First, referring to FIGS. 3 and 10-12 , the front shifting systemincludes a control unit 184, which may be a waterproof electronicdevice. The control unit 184 is attached to the front shift unit 150 byscrews or other fasteners 186. In this example, the control unit 184 isattached to the outboard or right side of the big chain ring 152. Thecontrol unit 184 contains a printed circuit board (PCB). The printedcircuit board may include a wireless radio and antenna, amicroprocessor, and spring-biased electrical contacts. During use, thewireless radio and antenna can send and receive shift commands to andfrom a rider-controlled actuator, such as the aforementioned shifter128, which may be located on the handlebar assembly 114 of the bicycle100. The wireless radio and antenna may also be used to communicate withthe electronic rear derailleur 126. The microprocessor can receive,process, and send out electronic signals. The microprocessor, wirelessradio, and antenna can be contained within a waterproof housing or case188 of the control unit 184.

The control unit 184 may also have a button 190 and a light emittingdiode (LED) 192 or other illumination element that are exposed on thehousing 188. The button 190 can be an electronic switch that is actuatedby the rider. The button 190 may be used for pairing the control unit184 of the front shift unit 150 with the shifter 128 on the handlebarassembly 114 and, optionally, for pairing the control unit 184 and thusthe front shift unit 150 with the electronic rear derailleur 126. TheLED 192 may be a multi-color LED, such as a red-green-blue (RGB) LED ora red-green-blue-white (RGBW) LED. The LED may thus be capable ofproducing light in three colors and be configured to provide visualfeedback to the rider to indicate a state of the front shifting system.Optionally, the printed circuit board may also include an electronicaudio or noise emitter that can provide audible feedback to the rider.

Referring to FIGS. 10-12 , the front shifting system includes a powersupply, which may be a rechargeable power supply 194 as describedherein, for providing power to operate the front shifting system. Inthis example, the power supply 194 is attached to the housing 188 of thecontrol unit 184. A latch 196 may be provided and actuated so that thepower supply 194 can be quickly and easily installed, removed, andreplaced by a rider without the use of a tool. The power supply 194 maybe a lithium-ion type rechargeable power supply or may be anothersuitable power supply type, if desired. When the power supply 194 isattached to the housing 188 of the control unit 184, the power supply isin electrical contact with the spring-biased electrical contacts and cansupply electrical energy to the PCB.

With continued reference to FIGS. 10-12 , the front shifting system alsoincludes a gearmotor unit 200, which may be a waterproofelectromechanical device. In this example, the gearmotor unit 200 ismounted to the right or outboard side of the big chain ring 152. Thegearmotor unit 200 may be attached via screws 202 or other suitablefasteners to a bracket 204 carried on the outboard side of the big chainring 152. The bracket 204 may likewise be attached or mounted to the bigchain ring 152 by similar fasteners or screws. Alternatively, thebracket 204 may be formed as an integral portion of the big chain ring152 or as an integral portion of a housing of the gearmotor unit 200 toreduce the number of parts to be assembled from three to two. Thegearmotor unit 200 can include an electric motor (not shown) and a geartrain (not shown). The gear train can be configured to reduce speed andincrease power output, i.e., output torque produced by the electricmotor of the gearmotor unit 200. The gear train can be internal to thegearmotor unit 200 and can be connected to and drive rotation of amechanical output portion of the gearmotor unit 200. The gearmotor unit200 can also include an angular position sensing system (not shown) thatsenses the angular position of the mechanical output portion ofgearmotor unit 200. The gearmotor unit 200 receives electric power andelectronic signals from the control unit 184 and can do so via anelectric cable (not shown).

The front shifting system also includes a chain guard or guard rail 206that is attached to the big chain ring 152 on the right side or outboardside. The chain guard rail 206 may be attached to the big chain ring 152by screws 208 or other suitable fasteners. The chain guard rail 206 issized and positioned to guide the chain 138, as necessary during use andwhile shifting, in order to help prevent the chain 138 from derailing tothe outboard side of big chain ring 152. The chain guard rail 206 isplaced adjacent the sprocket teeth 160 and spaced therefrom to theoutboard side. The chain guard rail 206 acts as an outboard directionbarrier for the chain 138.

The front shifting system further includes an upshift element 210 thatis carried on the big chain ring 152. In this example, the upshiftelement 210 is on the right side or outboard side of the big chain ring152 and is pivotable about its lower edge relative to the outboard side.In one example, the upshift element 210 can be made from aluminum sothat the element is lightweight and yet strong and durable. The upshiftelement 210 may be cast aluminum in one example. The upshift element 210is configured to selectively guide the chain 138 from the sprocket teeth162 of the small chain ring 154 to the sprocket teeth 160 of the bigchain ring 152, as described in further detail below. In an alternateexample, the upshift element 210 may be injection molded from a Nylonmaterial or a long fiber reinforced thermoplastic material. Variouscomponents of the upshift element 210, as described below, may also beattached separately to the upshift element 210 or may instead be moldedor otherwise formed as an integral portion of the element.

The front shifting system also includes at least one downshift elementcarried on the right side or outboard side of the big chain ring 152. Inthis example, the front shifting system includes two such elementsincluding a first downshift element 212 a and a second downshift element212 b, each being pivotable about a central portion thereof relative tothe outboard side. In one example, the first and second downshiftelements 212 a and 212 b are disposed generally 180 degrees opposite oneanother around the circumference of the front shift unit 150. In oneexample, each downshift element 212 a and 212 b can also be made fromaluminum so that each element is lightweight and yet strong and durable.The first and second downshift elements 212 a and 212 b may be castaluminum in one example. As with the upshift element 210, each downshiftelement 212 a and 212 b, in an alternate example, may be injectionmolded from a Nylon material or a long fiber reinforced thermoplasticmaterial.

In the disclosed example, the first downshift element 212 a and seconddownshift element 212 b have the same construction and configuration.Thus, only one downshift element may be shown or described in detailbelow. However, it should be understood that such illustrations anddescription may apply equally to either of the first and seconddownshift elements 212 a and 212 b. The first and second downshiftelements 212 a and 212 b are generally configured to selectively guidethe chain 138 from the sprocket teeth 160 of the big chain ring 152 tothe sprocket teeth 162 of the small chain ring 154, as described infurther detail below. As will become apparent below, the front shiftingsystem may include only one of the downshift elements or may includemore than two of the downshift elements, if desired.

Referring now to FIGS. 10, 11, and 13 , in this example, output torquefrom the electric motor of the gearmotor unit 200 is transferred to themechanical output portion of the gear motor unit. The mechanical outputportion of the gearmotor unit 200 is identified herein generally as amotor output 214, which can be in the form of an output shaft or a disc,bracket, horn, or the like coupled to such an output shaft via a splinedinterface or other suitable connection. The motor output 214 in thisexample may be axially retained to the gearmotor unit 200 by a screw orother suitable fastener (not shown). A hub 216 may be attached to themotor output 214, also by screws 218 or other suitable fasteners. Thehub 216 can be a circular disc or other suitable device for connectingthe gearmotor unit 200 to other components of the front shifting system.In this example, the hub has a circumferential slot 217 formed aroundthe perimeter of the hub. A first link 220 a and a second link 220 b areconnected to the hub 216. Each link 220 a and 220 b is a relativelythin, elongate element with a hole at each end. The hub 216 also has twoholes formed through the hub and may be disposed 180 degrees oppositeone another around the circumference of the hub. The proximal ends ofthe first link 220 a and second link 220 b are received in the slot 217with their holes aligned with a corresponding one of the two holes inthe hub 216. A first pin 222 a and a second pin 222 b are substantiallycylindrical in shape and are received through the corresponding holes inthe hub 216 and in the proximal ends of the respective links 220 a and220 b. The pins 222 a and 222 b are retained axially by retaining rings224 to secure the proximal ends of the links 220 a and 220 b to the hub216. In this way, the first link 220 a is rotatably attached to the hub216 via the first pin 222 a and the second link 220 b is rotatablyattached to the hub 216 via the second pin 222 b. Rotation of the hubvia the gearmotor unit 200 moves the first and second links 222 a and222 b as described further below.

FIGS. 14-16 show perspective and plan views of what is defined herein asa chain ring component 228, which includes the big chain ring 152 andthe small chain ring 154. As shown, the right side or outboard side ofthe big chain ring 152 with the components of the front shifting systemremoved. In this example, the outboard side of the big chain ring 152has a surface 226 with numerous optional features provided thereon.These optional features may each be integrally formed by a machining,casting, or other suitable process as an integrated part of the surface226 of the big chain ring 152. Alternatively, a number of these optionalfeatures may be formed as separate components and attached to thesurface 226 of the big chain ring 152 by welding, rivets, screws, orother suitable fasteners, or attachment techniques. In one example, thesurface 226 may include a shallow recessed landing 230 that is sized andconfigured to receive the housing 188 of the control unit 184 therein.The landing 230 can assist in providing an easily identifiable mountinglocation for properly positioning the control unit 184 when installed onthe surface 230. In another example, the surface 226 may include ashallow motor recess 232 that is sized and configured to receive thegearmotor unit 200 therein. The brackets 224, as noted above, may beintegrally formed as a part of the surface 226 or may be separatelyattached thereto adjacent the motor recess 232.

Further, a shallow pocket 234 may be formed having a semi-circular shapeto provide clearance depth in the surface 226 for the hub 216. Thepocket 234 may be formed adjacent the brackets 224 but on the oppositeside of the brackets relative to the motor recess 232. Recessed firstand second channels 236 a and 236 b may be formed extending in oppositedirections from the pocket 234 to accommodate the respective first andsecond links 220 a and 220 b (see also FIG. 13 ). The surface 226 alsoinclude an upshifter recess 238 formed having a semi-circular shape toaccommodate upshift driver and actuator components, as described below.A shaft support 240 is positioned adjacent to the upshifter recess 238and includes a bore 242 that extends through the support for receiving ashaft, also as described below. The surface 226 further includes a firstdownshifter recess 244 a, also formed having a semi-circular shape, toaccommodate a first downshift driver component, as described below. Ashaft support 246 is positioned adjacent to the first downshifter recess244 a and includes a bore 248 that extends through the support forreceiving a shaft, also as described below. The upshifter recess 238 andthe first downshifter recess 244 a are positioned spaced laterally aparton the surface 226. The shaft supports 240 and 246 are positioned sothat their respective bores 242 and 248 are concentrically aligned withone another. Further, the upshifter recess 238 is connected to the firstchannel 236 a so that the first link 220 a can extend from the hubpocket 234 to the upshifter recess 238 along the first channel.

The outboard side surface 226 of the big chain ring 152 further includesa second downshifter recess 244 b, also formed having a semi-circularshape, to accommodate a second downshift driver component, as describedbelow. A pair of spaced apart shaft supports 250 is positioned adjacentto and on opposite sides of the second downshifter recess 244 b. Each ofthe shaft supports 250 includes a bore 252 that extends through thesupport for receiving a shaft, also as described below. The shaftsupports 250 are positioned across the second downshifter recess 244 bfrom one another such that the bores 252 are concentrically aligned withone another. Further, the second downshifter recess 244 b is connectedto the second channel 236 b so that the second link 220 b can extendfrom the hub pocket 234 to the second downshifter recess 244 b along thesecond channel.

The surface 226 also includes a first downshift element depression 254 athat is positioned above and spaced from the first downshifter recess244 a. The first downshift element depression 254 a is shaped andconfigured to accommodate the first downshift element 212 a, asdescribed below. A pair of spaced apart shaft supports 256 is positionedadjacent to and on opposite sides of the first downshift elementdepression 254 a. Each of the shaft supports 256 includes a bore 258that extends through the support for receiving a shaft, also asdescribed below. The shaft supports 256 are positioned across the firstdownshift element depression 254 a from one another such that the bores256 are concentrically aligned with one another. The surface 226 furtherincludes a second downshift element depression 254 b that is positionedbelow and spaced from the second downshifter recess 244 b. The seconddownshift element depression 254 b is shaped and configured toaccommodate the second downshift element 212 b, as described below. Apair of spaced apart shaft supports 260 is positioned adjacent to and onopposite sides of the second downshift element depression 254 b. Each ofthe shaft supports 260 includes a bore 262 that extends through thesupport for receiving a shaft, also as described below. The shaftsupports 260 are positioned across the second downshift elementdepression 254 b from one another such that the bores 262 areconcentrically aligned with one another.

As noted above, since the first and second downshift elements 212 a and212 b have the same construction, the first and second downshift elementdepressions 254 a and 254 b can also have the same construction.However, the depressions 254 a and 254 b need not have the sameconstruction and can instead differ from one another as needed ordesired for a particular application.

Lastly, the big chain ring 152 has a series of holes 264 a-d that areprovided to accommodate a portion of the upshift element 210, asdescribed below. The series of holes 264 a-d are arranged in an arc andare spaced apart from one another in a circumferential direction on thebig chain ring 152. The series of holes 264 a-d are also graduallydifferent size and are arranged so that each successive hole is radiallyfurther away from the rotation axis R. In this example, the hole 264 ais closer to the rotation axis R and is the larger of the holes. Eachsuccessive hole 264 b-d is smaller than the prior hole and is furtherfrom the rotation axis R. More specifically, the hole 264 b is smallerand further from the axis R than the hole 264 a. The hole 264 c issmaller and further from the axis R than the hole 264 b. The hole 264 dis smaller and further from the axis R than the hole 264 c. In thisexample, there are four such holes 264 a-d in the series. This numbercan differ, as will become apparent to those having ordinary skill inthe art.

Referring to FIGS. 17 and 18 , the upshift element 210 is shown detachedfrom the front shift unit 150. In this example, the upshift element 210has a body 270 with some openings 272 formed through the material of thebody. The openings 272 may be provided to eliminate material of the body270 to reduce the weight of and the material usage to form the upshiftelement 210. The body 270 has an inboard facing side 274 with a seriesof contact surfaces 276 that are coplanar with one another and that lieon a chain ring contact plane C. A series of bores 278 a-e are providedthrough or in the body 270 of the upshift element 210. The series ofbores 278 a-e is arranged in an arc along the body 210. In this example,there are five such bores 278 a-e in the series. This number can alsodiffer, as will become apparent to those having ordinary skill in theart.

In this example, four of the bores 278 a-d of the series are eachconfigured to receive a chain guiding peg 280 therein. A fifth bore 278e of the series is configured to receive a chain upshifting hook 282therein. In this example, the chain guiding pegs 280 and the chainupshifting peg 282 may each be fixed to the body 270 of the upshiftelement 210 within the respective bores 278 a-e via a correspondingseries of set screws 284. The set screws 284 are exposed along a topedge of the body 270, which can generally follow the arc of the seriesof bores 278 a-e. The set screws 284 may be used to adjust and retain anangular or rotated position and an axial insertion or depth position ofthe chain guiding pegs 280 and the chain upshifting peg 282 relative tothe body 270 of the upshift element 210.

Referring to FIGS. 19-22 , each chain guiding peg 280 can be identicalin construction and thus only one is described in detail herein. In thisexample, the chain guiding peg 280 has a cylinder-shaped barrel end 286and a hook 288 projecting in an axial direction from the barrel end. Thebarrel end 286 is sized and configured to seat in one of the bores 278a-d. The hook 288 has an angled top surface 290 and the barrel end 286has an angled top portion 292 adjacent the angled top portion of thehook (see FIG. 22 ). Thus, the angled top surface 290 and angled topportion 292 are positioned to converge and meet between the barrel end286 and the hook 288 and are configured for contacting the chain 138, asdescribed below. The hook 288 also has an angled bottom surface 294opposite to and parallel with the angled top surface 292. The hook 288further has a plurality of chamfers 296 a-296 c on the tip and on edgesof the hook.

Referring to FIGS. 23-26 , the chain upshifting peg 282 can be differentfrom the chain guiding pegs 280. In this example, the chain upshiftingpeg 282 has a cylinder-shaped barrel end 300 and a hook 302 projectingin an axial direction from the barrel end. The barrel end 300 is sizedand configured to seat in the bore 278 e in the body 270 of theupshifting element 210. The hook 302 is L-shaped with a portion spacedfrom the barrel end 300 (see FIG. 26 ). The hook 302 has a chamfer 304at the tip and facing the barrel end 300. The hook 302 is configured tocontact and engage the chain 138, as described below. The hook 302 alsohas a chamfer 306 on the bottom that faces away from the barrel end 300and is opposite to and parallel with the chamfer 304 at the tip of thehook. The hook 302 also has a plurality of chamfers 308 a-308 c on thetip and on edges of the hook.

In this example, each of the chain guiding and chain upshifting pegs 280and 282 may be formed from a hardened steel for wear resistance,durability, and strength. However, these peg and hook elements may beformed of other suitable materials, if desired. In another example, theupshift element 210 and the chain guiding and chain upshifting pegs 280,282 may be formed as one integral unit from the same material, ifdesired. Also, each of the chain guiding pegs 280 may instead be formedas a unique element to present the hook at a different, required depth.Further, the bores 278 a-e can each be blind bores and the barrel ends286, 300 may each have a different length to automatically set the depthof each chain guiding and chain upshifting peg or element wheninstalled. The barrels and bores can also be configured with featuresthat will automatically set the rotational position of each peg wheninstalled. Further, each bore may have a different size to aid ininstalling the correct peg element in the correct bore on the upshiftelement 210.

As shown in FIG. 17 , the chain guiding pegs 280 and the chainupshifting peg 282 are arranged in a staggered, gradually recedinginsertion depth relative to the contact surfaces 276 on the body 270 andfrom the bore 278 a to the bore 278 e. More specifically, the angled topsurface 290 and the tip of each hook 288 for each successive chainguiding peg 280 from the bore 278 a to the bore 278 d is closer to theplane C of the contact surfaces 276 than the previous one. Likewise, thechamfer 304 and the tip of the hook 302 of the chain upshifting peg 282in the bore 278 e is closer to the plane C than the adjacent hook 288 ofthe chain guiding peg 280 in the bore 278 d. The purpose of this peg andhook arrangement is described in detail below.

The upshift element 210 also has a pair of gudgeons 310 that are spacedapart along and protrude from a bottom edge of the body 270. Eachgudgeon 310 has a through bore 312 oriented in a direction parallel withof the length of the body 270. The through bores 312 of the gudgeons 310are concentrically aligned with one another. The body 270 also has anadjustable set screw 314 extending widthwise or depth wise throughupshift element 210. The adjustable set screw 314 is threaded andengaged in a threaded hole through the body 270. The purpose andfunction of the set screw 314 are described below.

As noted above, the first and second downshift elements 212 a and 212 bhave the same configuration and construction in this example. FIGS.27-29 show the first downshift element 212 a, which is described in somedetail. The description is equally applicable to the second downshiftelement 212 b as well and thus each is shown and referenced herein withthe same features and reference numbers. In this example, the firstdownshift element 212 a includes a body 320 with a proximal end, adistal end, and a fulcrum 322 disposed generally between the ends. Apair of coaxial holes 324 are disposed spaced apart across a width ofthe body 320 and define a pivot axis P at the fulcrum 322.

The body 320 includes a drive arm 326 along one side of the body. Thedrive arm 326 extends radially relative to the axis P and from one ofthe holes 324 at the fulcrum 322. The free end of the drive arm 326 isthe proximal end of the body 320 in this example. A radial face of thedrive arm 326 defines a cam surface 328 of the downshift element 212 a.The cam surface 328 includes a notch 330. The other end of the body,opposite the drive arm 326, terminates at the distal end. The other endhas two legs 332 that extend radially relative to the axis P and from arespective one of the holes 324 at the fulcrum 322. A head 334 isconnected to the distal ends of the legs 332. The proximal end of thehead 334 connected to the legs 332 is thicker than the legs to define acontoured surface 336 (see FIG. 28 ) that faces radially inward towardthe fulcrum axis P. However, the contoured surface 336 has a non-flatcontour and is oriented at an angle, i.e., non-parallel relative to theaxis P (see FIGS. 27 and 29 ). The head 334 also defines a contact face338 on a tangential surface of the head. The contact face 338 is angled,i.e., non-parallel relative to a radial reference between the axis P andthe distal end of the downshift element 212 a. The contact face 338 isconfigured to engage the chain 138, as is described in more detailbelow.

In one example, the first and second downshift elements 212 a and 212 bmay be made from anodized aluminum. In another example, these elementsmay be made from other light weight, less expensive, and/or less durablematerials. However, in such an example, the head 334, or at least thecontact face 338 portion thereof, may be made separately from a moredurable, wear resistant material, such as hardened steel, and attachedto the head or to the body 320 of the downshift element.

Referring to FIGS. 30 and 31 , the upshift element 210 of the frontshifting system is associated with two upshift driving components thateffect movement of the upshift element, as described in greater detailbelow. In this example, one of the upshift driving components is anupshift driver 340 depicted in FIG. 30 . The upshift driver 340 has acylinder-shaped hub 342 with a central hole 344 formed axially throughthe hub. The upshift driver 340 rotates about the axis of the centralhole 344. Two torque protrusions 346 protrude axially from a face 347 ofthe hub 342. The torque protrusions 346 are wedge shaped and arepositioned 180 degrees opposite one another around the central hole 344.The torque protrusions 346 are configured to transmit torque during use,as described below.

A drive body 348 of the upshift driver 340 protrudes radially from thehub 342 relative to the axis of the central hole 344. A link hole 350 isformed through the drive body 348. The link hole 350 has an axis that isparallel to, but spaced radially apart from, the axis of the centralhole 344. A threaded bore 352 is formed radially into the hub 342 and isoriented perpendicular to axis of the central hole 344. A portion of thedrive body 348 forms a first spring contact surface 354 that isconfigured and arranged to engage a torsion spring or return spring, asdescribed below. In this example, the first spring contact surface 354faces radially inward toward the axis of the central hole 344 but liesin a plane that is spaced from or tangential relative to the axis.

In this example, the other of the upshift driving components is anupshift actuator 360 depicted in FIG. 31 . The upshift actuator 360 alsohas a cylinder-shaped hub 362 with a central hole 364 formed axiallythrough the hub. The upshift actuator 360 rotates about the axis of thecentral hole 364. Two torque protrusions 366 protrude axially from aface 368 of the hub 362. The torque protrusions 366 are also wedgeshaped and are also positioned 180 degrees opposite one another aroundthe central hole 364. The face 368 of the upshift actuator 360 contactsthe face 347 of the upshift driver 340 and the torque protrusions 366are configured to rotationally engage the torque protrusions 344 on theupshift driver 340 to transmit torque during use, as described below.

An actuator arm 370 of the upshift actuator 360 protrudes radially fromthe hub 362 relative to the axis of the central hole 364. A contactsurface 372 on the actuator arm 370 faces in a circumferentialdirection. The contact surface 372 is configured to contact a portion ofthe upshift element 210 to move the element during use, as is describedin further detail below. A portion of the actuator arm 370 forms asecond spring contact surface 374 that is configured and arranged toengage a torsion spring or return spring, as described below. In thisexample, the second spring contact surface 374 also faces radiallyinward toward the axis of the central hole 364 but lies in a plane thatis spaced from or tangential relative to the axis.

Referring to FIGS. 32 and 33 , the first downshift element 212 a of thefront shifting system is associated with two downshift drivingcomponents that effect movement of the first downshift element, asdescribed in greater detail below. In this example, one of the downshiftdriving components is a first downshift driver 380 depicted in FIG. 32 .The first downshift driver 380 also has a cylinder-shaped hub 382 with acentral hole 384 formed axially through the hub. The first downshiftdriver 380 also rotates about the axis of the central hole 384. Twotorque protrusions 386 protrude axially from a face 388 of the hub 382.The torque protrusions 386 are also wedge shaped and are positioned 180degrees opposite one another around the central hole 384. The torqueprotrusions 386 are configured to transmit torque during use, asdescribed below.

A protrusion 390 of the first downshift driver 380 protrudes radiallyfrom the hub 382 relative to the axis of the central hole 384. Athreaded bore 392 is formed radially into the hub 382 and is orientedperpendicular to axis of the central hole 384. An undercut portion ofthe protrusion 390 forms a first spring contact surface 394 that isconfigured and arranged to engage a torsion spring or return spring, asdescribed below. In this example, the first spring contact surface 394faces radially inward toward the axis of the central hole 384 but liesin a plane that is spaced from or tangential relative to the axis.

In this example, the other of the downshift driving components is afirst downshift cam 400 depicted in FIG. 33 . The first downshift cam400 has a cylinder-shaped hub 402 with a central hole 404 formed axiallythrough the hub. The first downshift cam 400 rotates about the axis ofthe central hole 404. Two torque protrusions 406 protrude axially from aface 408 of the hub 402. The torque protrusions 406 are also wedgeshaped and are also positioned 180 degrees opposite one another aroundthe central hole 404. The face 408 of the first downshift cam 400contacts the face 388 of the first downshift driver 380 and the torqueprotrusions 406 are configured to rotationally engage the torqueprotrusions 386 on the first downshift driver 380 to transmit torqueduring use, as described below.

A cam arm 410 of the first downshift cam 400 protrudes radially from thehub 402 relative to the axis of the central hole 404. A cam surface 412on the cam arm 410 faces in an outward radial direction at the end ofthe cam arm. The cam surface 412 is curved, may be concentric with theaxis of the central hole 404, and is configured to contact a portion ofthe first downshift element 212 a to move the element during use, as isdescribed in further detail below. An undercut portion of the cam arm410 forms a second spring contact surface 414 that is configured andarranged to engage a torsion spring or return spring, as describedbelow. In this example, the second spring contact surface 414 also facesradially inward toward the axis of the central hole 404 but lies in aplane that is spaced from or tangential relative to the axis.

Referring to FIGS. 34 and 35 , the second downshift element 212 b of thefront shifting system is also associated with two downshift drivingcomponents that effect movement of the second downshift element, asdescribed in greater detail below. In this example, one of the downshiftdriving components is a second downshift driver 420 depicted in FIG. 34. The second downshift driver 420 also has a cylinder-shaped hub 422with a central hole 424 formed axially through the hub. The seconddownshift driver 420 also rotates about the axis of the central hole424. Two torque protrusions 426 protrude axially from a face 428 of thehub 422. The torque protrusions 426 are also wedge shaped and arepositioned 180 degrees opposite one another around the central hole 424.The torque protrusions 426 are configured to transmit torque during use,as described below.

A lobe 430 of the second downshift driver 420 protrudes radially fromthe hub 422 relative to the axis of the central hole 424. A link hole432 is formed through the lobe 430. The link hole 432 has an axis thatis parallel to, but spaced radially apart from, the axis of the centralhole 424. An undercut portion of the lobe 430 forms a first springcontact surface 434 that is configured and arranged to engage a torsionspring or return spring, as described below. In this example, the firstspring contact surface 434 faces radially inward toward the axis of thecentral hole 424. A curved portion of the first spring contact surface434 is curved and is concentric with the axis of the central hole 424but spaced from the hub 422. A straight portion of the first contactsurface 434 lies in a plane that is spaced from or tangential relativeto the axis. A slot 436 is provided in the lobe 430 and extends in aplane perpendicular to the axis of the link hole 432. The slot 436 alsohas a depth whereby it fully intersects the link hole 432, whicheffectively divides the link hole 432 into two coaxial holes, one oneach side of the slot 436.

In this example, the other of the downshift driving components is asecond downshift cam 440 depicted in FIG. 35 . The second downshift cam440 is substantially similar to the first downshift cam 400 and thusalso has a cylinder-shaped hub 442 with a central hole 444 formedaxially through the hub. The second downshift cam 440 rotates about theaxis of the central hole 444. Two torque protrusions 446 protrudeaxially from a face 448 of the hub 442. The torque protrusions 446 arealso wedge shaped and are also positioned 180 degrees opposite oneanother around the central hole 444. The face 448 of the seconddownshift cam 440 contacts the face 428 of the second downshift driver420 and the torque protrusions 446 are configured to rotationally engagethe torque protrusions 426 on the second downshift driver 420 totransmit torque during use, as described below.

A cam arm 450 of the first downshift cam 440 protrudes radially from thehub 442 relative to the axis of the central hole 444. A cam surface 452on the cam arm 450 faces in an outward radial direction at the end ofthe cam arm. The cam surface 452 is curved, may be concentric with theaxis of the central hole 444, and is configured to contact a portion ofthe second downshift element 212 b to move the element during use, as isdescribed in further detail below. An undercut portion of the cam arm450 forms a second spring contact surface 454 that is configured andarranged to engage a torsion spring or return spring, as describedbelow. In this example, the second spring contact surface 454 also facesradially inward toward the axis of the central hole 444 but lies in aplane that is spaced from or tangential relative to the axis.

The assembled or installed configuration of the various componentsdescribed above is now provided below. Throughout the followingdescription of the assembled components of the front shift unit 150,continued reference to numerous different figures may be helpful.Specific figures are identified below when describing the components ofthe assembled front shift unit 150. However, there may also be otherfigures, though not specifically mentioned, that may be of interestbelow as well.

Referring to FIGS. 10-13 , a first cam shaft 460 extends between theshaft support 240 adjacent the upshifter recess 238 and the shaftsupport 246 adjacent the first downshifter recess 244 a on the big chainring 152 (see FIGS. 14 and 15 ). The first cam shaft 460 extends throughthe bores 242 and 248 (see FIGS. 14 and 16 ) of the corresponding shaftsupports 240 and 246. A retainer, such as a snap ring or a retainingring 462 (see FIG. 10 ) can be employed on at least one end or on bothends of the first cam shaft 460 to axially retain the shaft and preventit from being withdrawn from the bores 242, 248 in the shaft supports240, 246.

Referring to FIGS. 10-13 , the upshift element 210 is rotatablysupported on the first cam shaft 460 between the shaft supports 240 and246. More specifically, the first cam shaft is received through thebores 312 in the gudgeons 310 on the bottom edge of the body 270 of theupshift element 210. Referring also to FIGS. 5, 13-15, 18, 36, and 37 ,the series of bores 278 a-d in the upshift element 210 align withrespective ones of the series of holes 264 a-d in the big chain ring152. Thus, the teeth 288 on the chain guiding pegs 280, which are seatedin the bores 278 a-d in the body 270 of the upshift element 210, arepositioned to correspondingly align with the series of holes 264 a-d inthe big chain ring 152. Further, referring to FIGS. 5, 14, 15, 36, 37 ,the guard rail 206, which is mounted to the big chain ring 152, includesa bore 264 e that is positioned radially outboard of the big chain ring152. The hook 302 on the chain upshift peg 282, which is seated in thebore 278 e in the body 270 of the upshift element 210, is positioned tocorrespondingly align with the hole 264 e in the guard rail 206.

As can be seen in FIGS. 5, 14, 15, 36, and 37 , the big chain ring 152includes a gap 464 among the sprocket teeth 160 on the perimeter of thechain ring. The hole 264 e in the guard rail 206 is positioned to alignwith the gap 464. Thus, the hook 302 of the chain upshifting hook 282also aligned with the gap 464. As noted below, the series of holes 264a-d are arranged in an arc and are spaced apart from one another in acircumferential direction on the big chain ring 152. The series of holes264 a-d are also gradually arranged so that each successive hole isradially further away from the rotation axis R, with the hole 264 abeing closer to the rotation axis R and the hole 264 d being furtherfrom the rotation axis. The hole 264 e is positioned to follow the samearc whereby the hole is still further from the rotation axis R than theadjacent hole 264 d. In this example, the hole 264 e in the guard rail206 creates a fifth hole in the series of holes in the big chain ring152. Again, this number can differ, as will become apparent to thosehaving ordinary skill in the art.

When the upshift element 210 is mounted to the big chain ring 152, theupshift element can pivot about the axis of the first cam shaft 460toward and away from the big chain ring 152, as described further below.To accommodate, the teeth 288 of the chain guiding pegs 280 and the hook302 of the chain upshifting peg 282 are also arranged in the same arc asthe holes 264 a-e. Thus, the teeth 288 of the chain guiding pegs 280 canpass freely out of, and into and through, the corresponding holes 264a-d in the big chain ring 152. Likewise, the hook 302 of the chainupshifting peg 282 can pass freely out of, and into and through, thehole 264 e in the guard rail 206.

Referring to FIGS. 10-13 , an upshift biasing element, such as a torsionspring 466, can be provided to bias the upshift element 210 in a desireddirection. In this example, the torsion spring 466 is provided on thefirst cam shaft 460. The torsion spring 466 has a first leg 468 seatedin a notch 470 in the bottom edge on the body 270 of the upshift element210 and engages the upshift element. The torsion sprig 466 also has asecond leg 472 borne against the surface 226 of the big chain ring 152.The legs 468 and 472 of the torsion spring 466 bias the upshift element210 about the axis of the first cam shaft 460 in a direction toward thebig chain ring 152, which is counterclockwise in FIG. 13 .

The gearmotor unit 200 is seated in the motor recess 232 in the surface226 on the big chain ring 152. The hub 216 extending from the gearmotorunit 200 is positioned over the pocket 234. One end, the proximal end,of the first link 220 a is pivotally connected to the hub 216 by thefirst pin 222 a, which is received through the hole in the proximal endof the link and is retained by one of the retaining rings 224. The firstlink 220 a extends along the first recessed channel 236 a in the surface226 of the big chain ring 152. The upshift driver 340 is positioned overthe upshifter recess 238 and the first cam shaft 460 is received throughthe central hole 344 in the hub 342 of the upshift driver. A first drivepin 474 a is received through the link hole 350 in the drive body 348 onthe upshift driver 340 and though a hole in the other end, the distalend, of the first link 220 a. The first drive pin 474 a connects thefirst link 220 a to the upshift driver 340 and is retained by anotherretainer, such as a snap ring or retaining ring 476. In this way, thefirst link 220 a is rotatably connected to the upshift driver 340.Referring to FIGS. 10-12 and 30 , a set screw 478 is received in thethreaded bore 352 on the upshift driver 340. In this example, theinternal end of the set screw 478 can engage a flat surface (not shown)on the first cam shaft 460 to rotationally fix the upshift driver 340 tothe first cam shaft so that rotation of the upshift driver rotates thefirst cam shaft, as described below.

Referring to FIGS. 10-12 and 38 , the upshift actuator 360 is alsopositioned over the upshifter recess 238. The first cam shaft 460 isrotatably received through the central hole 364 in the hub 362 of theupshift actuator 360. The actuator arm 370 is positioned facing andwithin the upshifter recess 238. The upshift actuator 360 is positionedadjacent the upshift driver 340 on the first cam shaft 460 with theirrespective faces 368 and 347 closely confronting one another. The torqueprotrusions 366 of the upshift actuator 360 overlap axially with thetorque protrusions 346 on the upshift driver 340. Thus, the torqueprotrusion 366 and 346 can rotationally engage with one another. Anupshift biasing element, such as a torsion spring, i.e., an upshiftspring 480 is disposed on the first cam shaft 460 and axially betweenthe upshift driver 340 and the upshift actuator 360. A first leg (notshown) of the upshift spring 480 contacts or engages the first springcontact surface 354 on the upshift driver 340. A second leg 482 of theupshift spring 480 contacts or engages the second spring contact surface374 on the upshift actuator 360. The upshift spring 480 is disposed andarranged to rotationally bias the torque protrusions 346 on the upshiftdriver 340 against the torque protrusions 366 on the upshift actuator360, as shown in FIG. 38 .

Referring to FIGS. 10-12, 32, and 39 , the first downshift driver 380 ispositioned over the first downshifter recess 244 a and the first camshaft 460 is also received through the central hole 384 in the hub 382of the first downshift driver. A set screw 486 is received in thethreaded bore 392 on the first downshift driver 380. In this example,the internal end of the set screw 486 can engage another flat surface(not shown) on the first cam shaft 460 to rotationally fix the firstdownshift driver 380 to the first cam shaft so that rotation of thefirst cam shaft also rotates the first down shift driver, as discussedfurther below.

Referring to FIGS. 10-12 and 39 , the first downshift cam 400 is alsopositioned over the first downshifter recess 244 a. The first cam shaft460 is rotatably received through the central hole 404 in the hub 402 ofthe first downshift cam. The cam arm 410 is positioned facing and withinthe first downshifter recess 244 a. The first downshift cam 400 ispositioned adjacent the first downshift driver 380 on the first camshaft 460 with their respective faces 408 and 388 closely confrontingone another. The torque protrusions 406 of the first downshift cam 400overlap axially with the torque protrusions 386 on the first downshiftdriver 380. Thus, the torque protrusion 406 and 386 can rotationallyengage with one another. A first downshift biasing element, such as atorsion spring, i.e., a first downshift spring 490 is disposed on thefirst cam shaft 460 and axially between the first downshift driver 380and the first downshift cam 400. A first leg (not shown) of the firstdownshift spring 490 contacts or engages the first spring contactsurface 394 on the first downshift driver 380. A second leg 492 of thefirst downshift spring 490 contacts or engages the second spring contactsurface 414 on the first downshift cam 400. The first downshift spring490 is disposed and arranged to rotationally bias the torque protrusions386 on the first downshift driver 380 against the torque protrusions 406on the first downshift cam 400, as shown in FIG. 39 .

Referring to FIGS. 10-12, 14-16, and 39 , the first downshift element212 a is positioned over the first downshift element recess 254 a in thesurface 226 of the big chain ring 152. The fulcrum 322 of the firstdownshift element 212 a is received in the first downshift elementrecess 254 a. A first downshift shaft 496 a is received through thebores 258 of the supports 256 adjacent the first downshift elementrecess 254 a. The first downshift shaft 494 a is retained axially by aretaining element, such as a snap ring or retaining ring 498 a at eachend of the shaft. The first downshift shaft 496 a is also receivedthrough the holes 324 at the fulcrum 322 to pivotally support the firstdownshift element 212 a on the shaft and relative to the supports 256. Afirst downshifter biasing element, i.e., a first downshifter spring 500a, such as a torsion spring, may be disposed on the first downshiftshaft 496 a. A first leg (not shown) of the first downshifter spring 500a can engage the surface 226 of the big chain ring 152. A second leg 502of the first downshifter spring 500 a can engage a spring contactsurface 504 between the holes 324 of the fulcrum 322 on the firstdownshift element 212 a. The first downshift spring 500 a is configuredand arranged to bias the head 334 and contact face 338 of the firstdownshift element 212 a in a direction away from the big chain ring 152,the direction being counterclockwise in FIG. 39 .

Referring to FIGS. 10-13 and 40 , a second cam shaft 506 extends betweenthe shaft supports 250 adjacent the second downshifter recess 244 b onthe big chain ring 152 (see FIGS. 14 and 15 ). The second cam shaft 506extends through the bores 252 (see FIGS. 14 and 16 ) of the shaftsupports 250. A pair of retainers, such as snap rings or retaining rings508 (see FIG. 10 ) can be employed on the ends of the first cam shaft506 to axially retain the shaft and prevent it from being withdrawn fromthe bores 252 in the shaft supports 250.

Referring to FIGS. 10-13 and 34 , one end, the proximal end, of thesecond first link 220 b is pivotally connected to the hub 216 by thesecond pin 222 b, which is received through the hole in the proximal endof the second link and is retained by one of the retaining rings 224.The second link 220 b extends along the second recessed channel 236 b inthe surface 226 of the big chain ring 152. The second downshift driver420 is positioned over the second downshifter recess 244 b and thesecond cam shaft 506 is rotatably received through the central hole 424in the hub 422 of the second downshift driver. The other end, the distalend, of the second link 220 b is received in the slot 436 in the lobe430 of the second downshift driver 420A. A second drive pin 474 b isreceived through the link hole 432 in the lobe 430 and though a hole inthe distal end of the second link 220 b. The second drive pin 474 brotatably connects the second link 220 b to the second downshift driver420 and is retained by another retainer, such as a snap ring orretaining ring (not shown). In this way, the second link 220 b isrotatably connected to the second downshift driver 420 and drivesrotation of the second downshift driver 420, as described below.

Referring to FIGS. 10-13 and 40 , the second downshift cam 440 is alsopositioned over the second downshifter recess 244 b. The second camshaft 506 is rotatably received through the central hole 444 in the hub442 of the second downshift cam 440. The cam arm 450 is positionedfacing and within the second downshifter recess 244 b. The seconddownshift cam 440 is positioned adjacent the second downshift driver 420on the second cam shaft 506 with their respective faces 448 and 428closely confronting one another. The torque protrusions 446 of thesecond downshift cam 440 overlap axially with the torque protrusions 426on the second downshift driver 420. Thus, the torque protrusion 446 and426 can rotationally engage with one another. A second downshift biasingelement, such as a torsion spring, i.e., a second downshift spring 512is disposed on the second cam shaft 506 and axially between the seconddownshift driver 420 and the second downshift cam 440. A first leg (notshown) of the second downshift spring 512 contacts or engages the firstspring contact surface 434 on the second downshift driver 420. A secondleg 514 of the second downshift spring 512 contacts or engages thesecond spring contact surface 454 on the second downshift cam 440. Thesecond downshift spring 512 is disposed and arranged to rotationallybias the torque protrusions 426 on the second downshift driver 420against the torque protrusions 446 on the second downshift cam 440, asshown in FIG. 40 .

Referring to FIGS. 10-12, 14-16, and 40 , the second downshift element212 b is positioned over the second downshift element recess 254 b inthe surface 226 of the big chain ring 152. The fulcrum 322 of the seconddownshift element 212 b is received in the second downshift elementrecess 254 b. A second downshift shaft 496 b is received through thebores 262 of the supports 260 adjacent the second downshift elementrecess 254 b. The second downshift shaft 494 b is retained axially by aretaining element, such as a snap ring or retaining ring 498 b at eachend of the shaft. The second downshift shaft 496 b is also receivedthrough the holes 324 at the fulcrum 322 to pivotally support the seconddownshift element 212 b on the shaft and relative to the supports 260. Asecond downshifter biasing element, i.e., a second downshifter spring500 b, such as a torsion spring, may be disposed on the second downshiftshaft 496 b. A first leg (not shown) of the second downshifter spring500 b can engage the surface 226 of the big chain ring 152. A second leg502 of the second downshifter spring 500 b can engage a spring contactsurface 504 between the holes 324 of the fulcrum 322 on the seconddownshift element 212 b. The second downshift spring 500 b is configuredand arranged to bias the head 334 and contact face 338 of the seconddownshift element 212 b in a direction away from the big chain ring 152,the direction being counterclockwise in FIG. 40 .

The components of the front shifting system and the front shift unit 150can vary in configuration and construction from the example shown anddescribed herein. The specific components and component arrangement canalso vary. More specifically, the characteristics, such as the shape,size, depth, height, width, length, and location of the features,including the various shaft supports, recesses, holes, and depressions,on the surface 226 of the big chain ring 152 can also vary. Some of thefeatures and/or components may instead be part of or carried on thesmall chain ring 154 of the front shift unit 150. Also, the physicaldetails, such as the location, size, shape, structure, and material ofthe various drivers, actuators, cams, and upshift and downshift elementscan vary from the examples described above. The type, size, location,and arrangement of the various sub-components, including the cam shafts,pins, links, and biasing elements, can also vary from the examples shownand described herein. Also, details, such as the location, type,arrangement, size, physical input and output characteristics, electricalpower consumption, and mechanical power output, of theelectro-mechanical and electronic components, including the gearmotorunit and the control unit, can also vary from the examples disclosed anddescribed herein. As will be evident to those having ordinary skill inthe art upon reading this disclosure, the front shifting systemdisclosed and described herein can function as intended though changesare made to the component examples.

The operation of the front shifting system is now described withcontinued reference to the drawings, as noted below, and to the abovedescription of the components. The disclosed front shifting system hastwo shifting states and has two operational states. The operationalstates in this example include a first operational state, i.e., a bigchain ring state, and a second operational state, i.e., a small chainring state. In the big chain ring state, as shown in FIG. 2 , the chain138 is on the big chain ring 152 and remains engaged with the sprocketteeth 160 on the big chain ring with the bicycle 100 in a correspondinggear and a rider pedaling the bicycle. In the small chain ring state, asshown in FIG. 41 , the chain 138 is on the small chain ring 154 andremains engaged with the sprocket teeth 162 on the small chain ring withthe bicycle 100 in a corresponding gear and the rider pedaling thebicycle. One, more, or all of the front shifting system components maybe in certain positions and arrangements in the big chain ring state andin different positions and arrangements in the small chain ring state.Alternatively, one, more, or all of the front shifting system componentsmay be in the same positions and arrangements in each of the big chainring and small chain ring states. In such examples, the components ofthe front shifting system can move from the big and/or small chain ringstates to different, shifting states and arrangements in order to shiftthe chain 138 between the big and small chain rings 152 and 154.

The front shifting states include a first state, i.e., an upshift state,and a second state, i.e., a downshift state. In the upshift state, thefront shifting system and the components of the front shift unit 150 areoperated, positioned or repositioned, and arranged to shift the chain138 onto the big chain ring 152 and into engagement with the sprocketteeth 160 on the big chain ring. In the downshift state, the frontshifting system and the components of the front shift unit 150 areoperated, positioned or repositioned, and arranged to shift the chain138 onto the small chain ring 154 and into engagement with the sprocketteeth 162 on the small chain ring. By operating the front shiftingsystem, the chain 138 can be shifted or switched between the big andsmall chain rings to alter the gear rations of the drivetrain 124.

Referring first to FIGS. 2-6, 10, 11, 13, and 41-43 , the upshift stateof the front shift unit 150 is illustrated and the upshifting operationis now described. When a rider is riding the bicycle 100 in the smallchain ring operational state, as depicted in FIG. 41 , with the chain138 on and engaged with the small chain ring 154, the rider may shiftthe bicycle using the shifter 128. The rider may press a button on theshifter 128 to execute a gear shift or a shift change that results inthe chain 138 shifting from the small chain ring 154 to the big chainring 152. This operation is defined herein as an upshift or anupshifting operation. Actuating the shifter 128 results in a wirelesssignal being sent by a radio transmitter or transceiver of the shifterto the front shift unit 150. More specifically, the wireless signal maybe received by a radio receiver or transceiver on the PCB of the controlunit 184. The wireless signal may be processed by the microprocessor ofthe PCB and then a signal and power is transmitted to the gearmotor unit200.

The output portion 214 and hub 216 are driven by the gearmotor unit 200to rotate counterclockwise as depicted in and to the position shown inFIG. 13 . Rotation of the hub 216 in the counterclockwise directionmoves the first link 220 a down and the second link 220 b up in FIG. 13or, in other words, closer to the rotation axis R. This movement of thefirst link 220 a causes the upshift driver 340 to rotate in acounterclockwise direction to the position shown in FIG. 13 . Thismovement of the second link 220 b causes the second downshift driver 420to rotate in a clockwise direction to the position shown in FIG. 13 .

As the upshift driver 340 rotates counterclockwise to the position shownin FIGS. 13 and 38 , the torque protrusions 346 of the upshift driverengage the torque protrusions 366 of the upshift actuator 360 and rotatethe upshift actuator in the counterclockwise direction in the figure.During the upshifting operation, unlike in the downshifting operation asdescribed below, the upshift driver 340 directly drives rotation of theupshift actuator 360 without assistance or involvement of the upshiftspring 480. The upshift actuator 360 is then rotated to the positionshown in FIGS. 13 and 38 . In the position shown, the actuator surface372 on the actuator arm 370 of the upshift actuator 360 is clear andspaced from, and thus does not contact, the body 270 of the upshiftelement 210. The clearance between the actuator surface 372 on theactuator arm 370 and the body 270 of the upshift element 210 issufficient to allow the upshift element to rotate in thecounterclockwise direction toward the surface 226 of the big chain ring152. The biasing force applied by the torsion spring 466 against thebody 270 of the upshift element 210 drives rotation of the upshiftelement about the axis of the first cam shaft 460.

However, the upshift element 210 is only free to fully rotate into theposition shown in FIGS. 13 and 38 when the chain 138, which is on thesmall chain ring 154 as depicted in FIG. 41 , is not blocking any of theholes 264 a-264 d in the big chain ring 152 and the hole 264 e in theguard rail 206. The drivetrain 124 is operated in the direction of thearrow D, which rotates the gear shift unit 150 about the axis R, asshown in FIGS. 2 and 47 . The holes 264 a-264 e may be partially blockedby the chain 138 for at least a fraction of one drivetrain rotation. Asshown in FIG. 41 , the holes 264 a-264 e are clear of the chain 138 whenthe guard rail 206 and the upshift element 210 are positioned on a rearend or back end of the front shift unit 150 and between upper (forwardmoving direction) and lower (rearward return direction) segments of thechain. As soon as the holes 264 a-264 e are clear of the chain 138, thetorsion spring 466 biases the upshift element 210 to the position shownin FIGS. 13 and 38 adjacent the surface 226 of the big chain ring 152.

As the upshift element 210 rotates further in the counterclockwisedirection toward the surface 226 of the big chain ring 152, the chainguiding pegs 280 and the chain upshifting peg 282, each of which iscarried on the upshifting element 210, move through the correspondingholes 264 a-264 e toward a plane S defined by the sprocket teeth 162 ofthe small chain ring 154. The upshift element 210 rotates in thecounterclockwise direction until the contact surfaces 276 in the plane Con the body 270 abut or contact the surface 226 of the big chain ring152. The fully rotated upshift state of the upshift element 210 is shownin FIGS. 13 and 38 .

As described above, the upshift driver 340 and the first downshiftdriver 380 are both fixed, via the respective set screws 478 and 486, onand rotate in concert with the first cam shaft 460. Thus, rotation ofthe upshift driver 340 in the counterclockwise direction causes rotationof the first cam shaft 460, which in turn rotates the first downshiftdriver 380 in the same direction. This direction is counterclockwise inFIGS. 13 and 38 but is viewed as the clockwise direction in FIG. 39because the cross-section through the first downshifting components inthis figure is viewed from the opposite direction comparted tocomponents shown in cross-section in FIGS. 13 and 38 . As the firstdownshift driver 380 rotates in the clockwise direction in FIG. 39 , thetorque protrusions 386 on the first downshift driver engage the torqueprotrusions 406 on the first downshift cam 400, which then rotates thefirst downshift cam in the clockwise direction to the position shown inFIG. 39 .

In this position, the first downshift cam 400 does not contact the firstdownshift element 212 a. In the position shown, the cam surface 412 onthe cam arm 410 of the first downshift cam 400 is clear and spaced from,and thus does not contact the notch 330 on the cam surface 328 of thebody 320 of the first downshift element 212 a. The clearance between thecam surface 412 on the cam arm 410 of the first downshift cam 400 andthe cam surface 328 on the body 320 of the first downshift element 212 ais sufficient to allow the first downshift element to rotate in thecounterclockwise direction about the fulcrum axis P in FIG. 39 . Thefirst downshift element 212 a is rotated by the biasing force of thefirst downshifter spring 500 a. The first downshifter spring 500 abiases the first downshift element 212 a in the counterclockwisedirection in FIG. 39 and thus moves the contact face 338 on the head 334of the first downshift element 212 a away from a plane B defined by thesprocket teeth 160 of the big chain ring 152. In this upshifting state,as shown in FIG. 39 , the head 334 on the first downshift element 212 adoes not overlap the big chain ring 152, i.e., does not intersect theplane B. Again, during the upshifting operation, unlike in thedownshifting operation as described below, the first downshift driver380 directly drives rotation of the first downshift cam 400 withoutassistance or involvement of the first downshift spring 490.

Referring to FIGS. 2-6, 10, 11, 13, 40, and 41 , movements of the seconddownshift element 212 b and components for an upshifting operation andthe upshift state are similar to those of the first downshift element212 a. As noted above, the output portion 214 and hub 216 are driven bythe gearmotor unit 200 to rotate counterclockwise as depicted in and tothe position shown in FIG. 13 . Rotation of the hub 216 in thecounterclockwise direction moves the second link 220 b up in FIG. 13 or,in other words, closer to the rotation axis R. This movement of thesecond link 220 b causes the second downshift driver 420 to rotate in aclockwise direction to the position shown in FIG. 13 . This direction isclockwise in both of FIGS. 13 and 40 . As the second downshift driver420 rotates in the clockwise direction in FIG. 40 , the torqueprotrusions 426 on the second downshift driver engage the torqueprotrusions 446 on the second downshift cam 440, which then rotates thesecond downshift cam in the clockwise direction to the position shown inFIG. 40 .

In this position, the second downshift cam 440 does not contact thesecond downshift element 212 b. In the position shown, the cam surface452 on the cam arm 450 of the second downshift cam 440 is clear andspaced from, and thus does not contact the notch 330 on the cam surface328 of the body 320 of the second downshift element 212 b. The clearancebetween the cam surface 452 on the cam arm 450 of the second downshiftcam 440 and the cam surface 328 on the body 320 of the second downshiftelement 212 b is again sufficient to allow the second downshift elementto rotate in the counterclockwise direction about the fulcrum axis P inFIG. 40 . The second downshift element 212 b is rotated by the biasingforce of the second downshifter spring 500 b. The second downshifterspring 500 b biases the second downshift element 212 b in thecounterclockwise direction in FIG. 40 and thus moves the contact face338 on the head 334 of the second downshift element 212 b away from theplane B of the big chain ring 152. In this upshifting state, as shown inFIG. 40 , the head 334 on the second downshift element 212 b also doesnot overlap or intersect the plane B of the big chain ring 152. Again,during the upshifting operation, unlike in the downshifting operation asdescribed below, the second downshift driver 420 directly drivesrotation of the second downshift cam 440 without assistance orinvolvement of the second downshift spring 512.

In each of FIGS. 2-6, 10, 11, 13, 38-43 , the front shifting system andthe front shift unit 150 is depicted in the upshift state, as describedabove. However, the upshifting operation has not yet taken place. Theangled contact surfaces 338 of the first and second downshift elements212 a and 212 b are biased outward away from the plane B of the bigchain ring 152. Thus, the downshift elements 212 a and 212 b arepositioned so as not to interfere with the chain 138 as the drivetrain124 is operated by a rider and as the chain upshifts. Likewise, thechain guiding pegs and the chain upshifting peg protrude through theholes 264 a-264 e in the big chain ring 152 and are positionedrelatively close to the plane S of the small chain ring 154 and areready to execute an upshift.

After the rider has actuated the shifter 128 to execute an upshift orupshifting operation, as the rider continues to pedal, the chain 138 isreleased from the small chain ring 154 and upshifts from the small chainring 154 to the big chain ring 152, as shown sequentially in FIGS. 41and 47-52 . Referring to FIG. 41 , the chain 138 is carried on the smallchain ring 154 and the rider is pedaling the drivetrain 124, and thesmall chain ring, in the direction of the arrow D. The chain guidingpegs 280 and chain upshifting peg 282 are approaching from under, buthave not yet reached, the chain 138. Referring to FIG. 47 , a first orleading chain guiding peg 280, which is protruding through the hole 264a of the big chain ring 152, encounters the chain 138 and begins toengage the chain.

FIGS. 7-9 depict various views of the chain 138 and FIG. 53 depicts across-section of the chain and the lead chain guiding peg 280 as thehook 288 engages the chain. The chain 138 and the sprocket teeth 162 onthe small chain ring 154 are timed or synced such that the tip of thehook 288 on the chain guiding peg 280 rises into the tooth space 170between a pair of the outer plates 168 of a chain link. As the ridercontinues to pedal and the front shift unit 150 continues to rotate inthe arrow D direction, the chain link of the chain 138 is held by thehook 288 of the chain guiding peg 280 in a position that is further awayin a radial direction from the rotation axis R of the front shift unit150 compared to the position of the links of the chain forward of thechain guiding peg 280 and engaged with the small chain ring 154. Theouter plates 168 of the link on the hook 288 slide down from the tip ofthe hook along the angled top surface 290 (or the hook drives up intothe tooth space 170) from the position shown in FIG. 53 to the positionshown in FIG. 54 . Thus, the chain 138 moves a relatively small distanceto the right or the outboard direction away from the plane C of thesmall chain ring 154 toward the plane B of the big chain ring 152.

FIGS. 48-50 show the subsequent sequential engagement of the remainderof the chain guiding pegs 280 with the chain 138 as the rider continuesto pedal. As noted above, the chain guiding pegs 280 and the chainupshifting peg 282 are positioned gradually further outward in a radialdirection relative to the rotation axis R of the front shift unit 150.Likewise, each of the teeth 288 and 302 of the chain guiding pegs 280and chain upshifting peg 282 is positioned axially further from theplane C of the small chain ring 154. As shown in FIG. 48 , the nextsubsequent chain guiding peg 280, which protrudes through the hole 264 bin the big chain ring 154, enters the tooth space 170 between andengages the outer plates 168 of a subsequent or trailing link of thechain 138. As the rider continues to pedal, the chain link of the chain138 is held by the next subsequent hook 288 in a position that isfurther away in a radial direction from the rotation axis R compared tothe position of the links of the chain engaged with the leading chainguiding element 280. Also, the tip of the next subsequent hook 288enters the tooth space 170, as in FIG. 53 . The outer plates 168 of thelink on the hook 288 again slide down or move relative to the tip of thehook along the angled top surface 290 from the position shown in FIG. 53to the position shown in FIG. 54 . Thus, the chain 138 again moves arelatively small distance to the right or the outboard direction furtheraway from the plane C of the small chain ring 154 toward the plane B ofthe big chain ring 152 and relative to the position of the chain on theleading chain guiding peg 280.

Referring to FIGS. 49 and 50 , each of the next two subsequent chainguiding pegs 280, which protrude through the holes 264 c and 264 d, willfunction in the same manner as the leading chain guiding peg 280 and thenext subsequent chain guiding peg. Thus, the chain 138 will be guidedfurther outward in a radial direction away from the rotation axis R bythe sequence of chain guiding pegs 280 because the teeth 288 arepositioned sequentially further from the axis. The chain 138 will alsobe guided further outboard toward the plane B of the big chain ring 152by the sequence of teeth 288 on the chain guiding pegs 280 because theteeth are positioned sequentially closer to the plane B.

Referring to FIG. 51 , the chain upshifting peg 282 then subsequentlyengages a further trailing link of the chain 138. Referring to FIG. 55 ,a tip of the hook 302 of the chain upshifting peg 282 is positioned inthe tooth space 170 between a pair of outer plates 168 of the link. Asthe rider continues to pedal, the link of the chain 138 is held by chainupshifting peg in a position that is again further outward in a radialdirection from the rotation axis R compared to the preceding link on thepreceding adjacent chain guiding peg 280. The link of the chain 138 alsoslides down along the chamfered top surface 304 of the hook 302 from theposition shown in FIG. 55 to the position shown in FIG. 56 . This movesthe link of the chain 138 into alignment with plane B of the big chainring 152. Subsequent links of the chain 138 will then engage with thesprocket teeth 160 on the big chain ring 152. As the rider continues topedal and the front shift unit 150 continues to rotate about therotation axis R, the chain will become fully engaged with the big chainring 152, as shown in FIGS. 2 and 52 .

As noted above, the sprocket teeth 160 on the big chain ring 152 caninclude alternating narrow teeth 160 n and wide teeth 160 w, which canrespectively engage the narrow tooth spaces 166 between the inner plates164 (i.e., narrow links) and the wide tooth spaces 170 between the outerlinks 168 (i.e., wide links) of the chain. The small chain ring 154 canalso include such alternating narrow teeth 162 n and wide teeth 162 w.In this example, the chain guiding pegs 280 and chain upshifting peg 282are timed or synced and spaced to engage the wide chain links and theteeth 288 and 302 are sized to engage the wide tooth spaces 170.However, the chain guiding pegs and chain upshifting peg, and therespective teeth, can be sized and spaced to engage alternating wide andnarrow links and tooth spaces of the chain or to engage only the narrowlinks and tooth spaces of the chain.

The guard 206 may be configured to have a specific height to protrude adesired radial distance outward relative to the position of the sprocketteeth 160. The guard rail 206 may also be configured to have a specificlength to cover a desired degree of arc of the big chain ring 152.Likewise, the guard rail 206 can be placed on the big chain ring 152relative to the chain upshifting peg 282 and spaced a desired distanceto the outboard side of the big chain ring in order to limit outboardtravel of the chain 138 as it upshifts onto the big chain ring. In otherwords, the guard rail 206 can be sized, shaped, and positioned asnecessary to allow the chain 138 to engage the sprocket teeth 160 whilepreventing the chain from derailing to the outboard side of big chainring during the upshifting operation. As the rider continues to pedalwith chain 138 engaged with the big chain ring 152, as shown in FIGS. 2and 52 , the chain upshifting peg 282 and hook 302 can remain alignedwith the plane B of the big chain ring 152. Thus, the hook 302 mayeffectively act as an axial guide replacing or formed as a sprockettooth of big chain ring 152. The front shifting system and thecomponents of the front shift unit 150 remain in the upshift state inthis example until the rider requests or executes a downshift.

Referring next to FIGS. 12 and 44-46 , the downshift state of the frontshift unit 150 is illustrated and the downshifting operation is nowdescribed. When the rider is riding the bicycle 100 and the chain 138 isengaged with the big chain ring 152 as in FIGS. 2 and 52 , the rider maywish to change gears. The gear change may require a downshift operationof the front shift unit 150 that shifts the chain 138 from the big chainring 152 to the small chain ring 154. The rider may press a button oroperate an actuator of the shifter 128 on the handlebar assembly 114. Awireless signal is then sent to the front shift unit 150 and is againreceived by the radio or wireless receiver or transceiver on the PCB ofthe control unit 184 The processor or microprocessor of the control unit184 then processes the signal and an appropriate signal and power issent to the gearmotor unit 200.

During the downshift operation, the gearmotor unit 200 is operated todrive or rotate the output portion 214 in a clockwise directionreferring to FIGS. 13 and 46 . Operation of the gearmotor unit 200 andthe output portion 214 in the clockwise direction causes the hub 216 toalso rotate clockwise from the position shown in FIG. 13 to the positionshown in FIG. 46 . Rotation of the hub 216 in the clockwise directiondrives movement of the first link 220 a upward and the second link 220 bdownward to the positions shown in FIG. 46 . Upward movement of thefirst link 220 a rotates the upshift driver 340 in a clockwisedirection.

Referring to FIGS. 38 and 57 , as the upshift driver 340 rotates in theclockwise direction, the biasing force of the upshift spring 480 causesthe upshift actuator 360 to also rotate in the clockwise direction inconcert with the upshift driver 340. This rotation keeps the torqueprotrusions 366 of the upshift actuator 360 firmly biased against and incontact with the torque protrusions 346 of the upshift driver 340. Asthe upshift actuator 360 rotates in the clockwise direction, theactuator surface 372 of the upshift actuator 360 comes into contact andbears against the inboard side or face on the body 270 of the upshiftelement 210. This rotation of the upshift actuator 360 thus biases orrotates the upshift element 210 also in the clockwise direction awayfrom the surface 226 of the big chain ring 152. Rotation of the upshiftelement 210 in the clockwise direction of FIGS. 38 and 57 will thuswithdraw the chain guiding pegs 280 and chain upshifting peg 282, andtheir corresponding teeth 288 and 302, away from the plane S of thesmall chain ring 154 and thus from the holes 264 a-264 e.

It is possible that the rider may attempt to execute a downshift whilethe upshift element 210 is blocked from rotation in the clockwisedirection away from the big chain ring 154. This may occur when thechain 138 is blocking rotation of the upshift element 210. For example,the chain 138 may block rotation of the upshift element 210 when thechain is on the big chain ring 152 as in FIG. 2 but is still engagedwith the hook 302 of the chain upshifting peg 282 on the upshiftelement. When this occurs, the upshift element 210 and the upshiftactuator 360 will remain stationary as the upshift driver 340 continuesto rotate. As this occurs, the torque protrusions 346 of the upshiftdriver 340 will separate or move apart from the torque protrusions 366of the upshift actuator 360. The upshift spring 480 will thus wind upand store energy. The upshift element 210 will eventually become free torotate in the clockwise direction, such as when the crank assembly 132rotates to a position where the hook 302 on the chain upshifting peg 282becomes free of the chain 138. When the upshift element 210 is free torotate, the upshift element and the upshift actuator 360 will rotate inthe clockwise direction under the biasing force of the upshift spring480 to the position shown in FIG. 57 .

As the upshift element 210 rotates in the clockwise direction, the chainguiding pegs 280 and the chain upshifting peg 282, as noted above, moveaway from the plane S of the small chain ring 154 and clear the holes264 a-264 e. When the upshift element 210 is in the state as shown inFIGS. 38 and 57 , the direction or orientation of any force vector thatmight be transmitted through the first link 220 a passes substantiallyalong the lengthwise axis of the first link and through the rotationaxis of the gearmotor unit, i.e., the center of rotation of the hub 216.In other words, if the upshift element 210 is subjected to an externalforce in the inboard or counterclockwise rotation direction (or even inthe opposite direction), such as if the upshift element is struck by anobject or is accidentally bumped by the rider, the force will not causethe hub 216 or the gearmotor unit 200 to be back driven or reverserotated. This is because any such force vector is applied via the body270 of the upshift element 210, through the upshift actuator 360 andupshift driver 340, and through the first link 220 a and will this nottend to cause any rotation of the hub 216.

The set screw 314 along the lower edge of the body 270 on the upshiftelement 210, which may be threadably received through the body, may berotated or adjusted to fine tune or adjust the position of the upshiftelement 210. The set screw 314 may be located on the body 270 of theupshift element 210 such that the actuator surface 372 on the upshiftactuator contacts the free end of the set screw protruding from thebody, instead of the upshift actuator directly contacting the upshiftelement 210. Alternatively, the free end of the set screw 314 may bepositioned to contact the surface 226 of the big chain ring 152. Ineither case, the adjusted position of the set screw 314 can be used todetermine the furthest inboard rotation position of the upshift element210, which is biased toward the surface 226 of the big chain ring 152 bythe torsion spring 466.

As described above, the upshift driver 340 and the first downshiftdriver 380 are both fixed to the first cam shaft 460 via the previouslydescribed set screws 478 and 486. Thus, rotation of the upshift driver340 in the clockwise direction of FIGS. 38 and 57 also drives rotationof the first cam shaft 460, and thus the first downshift driver 380, inthe same clockwise direction. Referring to FIGS. 39 and 58 , the firstdownshift element 212 a is shown from the opposite side compared toFIGS. 38 and 57 . Thus, the aforementioned clockwise rotation of thefirst downshift driver 380 in FIGS. 38 and 57 is shown in reverse orcounterclockwise in FIGS. 39 and 58 . As the first downshift driver 380rotates in the counterclockwise direction in FIGS. 39 and 58 , thebiasing force of the first downshift spring 490 drives the firstdownshift cam 400 to rotate in the counterclockwise direction in concertwith the first downshift driver 380. The torque protrusions 406 of thefirst downshift cam 400 contact and are firmly biased against the torqueprotrusions 386 of the first downshift driver 380. As the firstdownshift cam 400 rotates in the counterclockwise direction in FIG. 58 ,the cam surface 412 on the cam arm 410 of the first downshift cam comesinto contact with the cam surface 328 on the drive arm 326 of the firstdownshift element 212 a. This rotates the first downshift element 212 ain the clockwise direction in FIGS. 39 and 58 about the first downshiftshaft 496 a. The first downshift element 212 a is rotated by this actionfrom the position shown in FIG. 39 to the position shown in FIG. 58 .

Similar to the circumstance described above for the upshift element 210,the first downshift element 212 a may be unable to immediately rotate inthe clockwise direction upon an attempted execution of a downshift. Forexample, the chain 138 will block movement of the first downshiftelement 212 a if the first downshift element tries to move toward theplane B of the big chain ring 152 while the chain 138 is on the sprocketteeth 160 of the big chain ring. The head 334 on the body 320 of thefirst downshift element 212 a will instead contact the side of the chain138. If this occurs, the first downshift element 212 a and the firstdownshift cam 400 will remain stationary as the first downshift driver380 continues to rotate, being driven by rotation of the first cam shaft460. The torque protrusions 386 on the first downshift driver 380 willrotate away and come out of contact with the torque protrusions 406 onthe first downshift cam 400. As a result, the first downshift spring 490will wind up and store energy. As the crank assembly 132 continues torotate, the first downshift element 212 a will eventually become free torotate toward the plane B of the big chain ring 152. This occurs whenthe first downshift element 212 a is positioned on the rear of the bigchain ring 152 where the chain 138 is not engaged with the sprocketteeth 160 on the big chain ring. This position is shown in FIG. 52 wherethe first downshift element 212 a is rising upward toward the chain 138but is adjacent a rear portion of the big chain ring 152 that is notengaged with the chain.

When the first downshift element 212 a is free to rotate, the firstdownshift cam 400 will rotate in the counterclockwise direction in FIGS.39 and 58 under the biasing force of the first downshift spring 490.Rotation of the first downshift cam 400 will drive rotation of the firstdownshift element 212 a in the clockwise direction of FIGS. 39 and 58about the first downshift shaft 496 a. As the first downshift element212 a rotates in the clockwise direction, the angled contact face 338 onthe head 334 of the first downshift element moves toward the plane B ofthe big chain ring 152 until the head overlaps the plane and thesprocket teeth 160, as shown in FIGS. 46 and 58 . In this state, firstdownshifter spring 500 a biases the first downshift element 212 a in thecounterclockwise direction in FIG. 58 away from the plane B of the bigchain ring 152. Thus, the first downshifter spring 500 a biases the camsurface 328 on the drive arm 326 of the first downshift element 212 aagainst the curved cam surface 412 of the first downshift cam 400, whichholds the first downshift element 212 a in the downshift stateoverlapping the plane B of the big chain ring 152.

If the first downshift element 212 a experiences an external force thatwould otherwise move the first downshift element in the counterclockwisedirection in FIG. 58 , the first downshift element would remainstationary in this state. For example, as the first downshift element212 a rises from under the chain 138 in FIG. 52 into contact with thechain, the force of the chain, and the force of the first downshifterspring 500 a, would tend to rotate the first downshift element about thefirst downshift shaft 496 a in the counterclockwise direction, pushingthe head 334 outboard away from the plane B. However, the firstdownshift element 212 a in this downshift state is unable to move in thecounterclockwise direction in FIG. 58 because the drive arm 326 on thebody 320 of the first downshift element 212 a is borne against andblocked by the cam surface 412 of the first downshift cam 400. In oneexample, the curvature of the cam surface 412 may be cylindricallyshaped and concentric with the axis of the first cam shaft 460. Thus,any force vector exerted by the cam surface 328 on the drive arm 326 ofthe first downshift element 212 a against the cam surface 412 of thefirst downshift cam 400 in the downshift state of FIG. 58 would passthrough the axis of the first cam shaft 460. As a result, no amount ofexternal force exerted by the chain 138 on the head 334 of the firstdownshift element 212 a in this downshift state would tend to causerotation of first downshift cam 400 about the first cam shaft 460. Theforce of the chain 38 thus will not cause the first downshift cam 400 orthe first downshift element 212 a to be back driven or reverse rotatedaway from the plane B of the big chain ring 152.

At this point, the front shifting system is in the downshift state, buta downshift has not yet been described or completed. Referring to FIGS.46, 52, 57, and 58 , the angled contact face 338 on the head 334 of thefirst downshift element 212 a is biased to overlap the plane B of thebig chain ring 152. Likewise, the upshift element 210 including thechain guiding pegs 280 and the chain upshifting peg 282 are biased in adirection away from the plane S of the small chain ring 154. As therider continues to pedal from the position of the front shift unit inFIG. 52 , the chain 138 downshifts from the sprocket teeth 160 of thebig chain ring 152 to the small chain ring 154 as shown in FIG. 59 .More specifically, as the first downshift element 212 a rises intocontact with the chain 138, the angled contact face 338 on the firstdownshift element blocks the chain from engaging the sprocket teeth 160on the big chain ring 152. Instead, the angled contact face 338 forcesthe chain 138 to redirect or deflect out of alignment with the plane Bof the big chain ring in the inboard direction toward the plane S of thesmall chain ring 154. As the rider continues to pedal the front shiftunit 150 in the rotation direction R, the chain 138 will continue towrap around and engage the sprocket teeth 162 of the small chain ring154 as depicted in FIGS. 41 and 47 . After the downshift operation iscomplete, the front shifting system in this example remains in thedownshift state until the rider requests or executes an upshift, asdescribed above.

In one example, the outboard side surface 226 on the big chain ring 152may include an elongate recess 520 associated with the position of eachof the downshift elements, which includes the first and second downshiftelements 212 a and 212 b in this example. These recesses 520 can extendfrom the outermost radius of the big chain ring 152 where the head 334of each downshift element is positioned adjacent the sprocket teeth 160.The recesses 520 can extend in a gradual spiral direction inward towardthe sprocket teeth 162 of the small chain ring 154. The recesses 520 canaid the chain 138, by providing sufficient clearance between the chainand the surface 226, when downshifting to the sprocket teeth 162 on thesmall chain ring 154, as depicted in FIG. 59 with respect to the firstdownshift element 212 a.

In the disclosed example, the front shifting unit 150 has another, i.e.,the second downshift element 212 b as noted earlier, not just the one orfirst downshift element 212 a, which is described above in detail.Referring again to FIGS. 12 and 44-46 , the downshift state of the frontshift unit 150 is illustrated. During the above described downshiftoperation, when the rider presses a button or operates an actuator ofthe shifter 128 on the handlebar assembly 114, a wireless signal is sentto the front shift unit 150. The wireless signal is again received bythe radio or wireless receiver or transceiver on the PCB of the controlunit 184. The processor or microprocessor of the control unit 184 thenprocesses the signal and an appropriate signal and power is sent to thegearmotor unit 200. When the first downshift element 212 a is actuatedor moved to the downshift state, the second downshift element 212 b isalso moved or actuated to the downshift state

Referring to the assembled front shift unit of FIGS. 10-12 , thecross-section views of FIGS. 13 and 46 , and the enlarged cross-sectionviews of FIGS. 40 and 60 , the movements of the second downshift element212 b and the corresponding components are now described during thedownshift operation. During the downshift operation, the gearmotor unit200 drives or rotates the output portion 214 and thus the hub 216 in theclockwise direction from the position shown in FIG. 13 to the positionshown in FIG. 46 . Rotation of the hub 216 in the clockwise directiondrives movement of the second link 220 b downward from the positionshown in FIG. 13 to the position shown in FIG. 46 . Downward movement ofthe second link 220 b rotates the second downshift driver 420 in thecounterclockwise direction from the position shown in FIG. 13 to theposition shown in FIG. 46 about the second cam shaft 506.

As the second downshift driver 420 rotates in the counterclockwisedirection in FIGS. 40 and 60 , the biasing force of the second downshiftspring 512 drives the second downshift cam 440 to rotate in thecounterclockwise direction in concert with the second downshift driver420. The torque protrusions 446 of the second downshift cam 440 contactand are firmly biased against the torque protrusions 426 of the seconddownshift driver 420. As the second downshift cam 440 rotates in thecounterclockwise direction in FIG. 60 , the cam surface 452 on the camarm 450 of the second downshift cam comes into contact with the camsurface 328 on the drive arm 326 of the second downshift element 212 b.This rotates the second downshift element 212 b in the clockwisedirection in FIGS. 40 and 60 about the second downshift shaft 496 b. Thesecond downshift element 212 b is rotated by this action from theposition shown in FIG. 40 to the position shown in FIG. 60 .

Similar to the circumstance described above for the first downshiftelement 212 a, the second downshift element 212 b may be unable toimmediately rotate in the clockwise direction toward the plane B of thebig chain ring 152 upon an attempted execution of a downshift. Forexample, the chain 138 will again block movement of the second downshiftelement 212 b if the second downshift element tries to move toward theplane B of the big chain ring 152 while the chain 138 is on the sprocketteeth 160. The head 334 on the body 320 of the second downshift element212 b will instead contact the side of the chain 138. If this occurs,the second downshift element 212 b and the second downshift cam 440 willremain stationary as the second downshift driver 420 continues torotate, being driven by rotation of the hub 216 and the second link 220b. The torque protrusions 426 on the second downshift driver 420 willrotate away and come out of contact with the torque protrusions 446 onthe second downshift cam 440. As a result, the second downshift spring512 will wind up and store energy. As the crank assembly 132 continuesto rotate, the second downshift element 212 b will eventually becomefree to rotate toward the plane B of the big chain ring 152. Again, thisoccurs when the second downshift element 212 b is positioned on the rearof the big chain ring 152 where the chain 138 is not engaged with thesprocket teeth 160 on the big chain ring. This position is not shown(though it would be similar to the position of the first downshiftelement 212 a in FIG. 52 ) but would occur when the second downshiftelement 212 b is rising upward toward the chain 138 but is adjacent arear portion of the big chain ring 152 that is not engaged with thechain.

When the second downshift element 212 b is free to rotate, the seconddownshift cam 440 will rotate in the counterclockwise direction in FIGS.40 and 60 under the biasing force of the second downshift spring 512.Rotation of the second downshift cam 440 will drive rotation of thesecond downshift element 212 b in the clockwise direction of FIGS. 40and 60 about the second downshift shaft 496 b. As the second downshiftelement 212 b rotates in the clockwise direction, the angled contactface 338 on the head 334 of the second downshift element moves towardthe plane B of the big chain ring 152 until the head overlaps the planeand the sprocket teeth 160, as shown in FIGS. 46 and 60 . In this state,second downshifter spring 500 b biases the second downshift element 212b in the counterclockwise direction in FIG. 60 away from the plane B ofthe big chain ring 152. Thus, the second downshifter spring 500 b biasesthe cam surface 328 on the drive arm 326 of the second downshift element212 b against the curved cam surface 452 of the second downshift cam440, which holds the second downshift element 212 b in the downshiftstate overlapping the plane B of the big chain ring 152.

As with the first downshift element 212 a described above, if the seconddownshift element 212 b experiences an external force that wouldotherwise move the second downshift element in the counterclockwisedirection in FIG. 60 , the second downshift element would remainstationary in this state. For example, as the second downshift element212 b rises from under the chain 138 (not shown) into contact with thechain, the force of the chain, and the force of the second downshifterspring 500 b, would tend to rotate the second downshift element aboutthe second downshift shaft 496 b in the counterclockwise direction,pushing the head 334 outboard away from the plane B. However, the seconddownshift element 212 b in this downshift state is unable to move in thecounterclockwise direction in FIG. 60 because the drive arm 326 on thebody 320 of the second downshift element 212 b is borne against andblocked by the cam surface 452 of the second downshift cam 440. Again,the curvature of the cam surface 452 may be cylindrically shaped andconcentric with the axis of the second cam shaft 506. Thus, any forcevector exerted by the cam surface 328 on the drive arm 326 of the seconddownshift element 212 b against the cam surface 452 of the seconddownshift cam 440 in the downshift state of FIG. 60 would pass throughthe axis of the second cam shaft 506. As a result, no amount of externalforce exerted by the chain 138 on the head 334 of the second downshiftelement 212 b in this downshift state would tend to cause rotation ofsecond downshift cam 440 about the second cam shaft 506. The force ofthe chain 38 thus will not cause the second downshift cam 440 or thesecond downshift element 212 b to be back driven or reverse rotated awayfrom the plane B of the big chain ring 152.

As with the first downshift element 212 a, at this point, the frontshifting system is in the downshift state, but a downshift has not yetbeen completed. Referring to FIGS. 46, 52 (for general reference), and60, the angled contact face 338 on the head 334 of the second downshiftelement 212 b is biased to overlap the plane B of the big chain ring152. The upshift element 210 including the chain guiding pegs 280 andthe chain upshifting peg 282 are biased in a direction away from theplane S of the small chain ring 154. As the rider continues to pedalfrom a position of the front shift unit 150 that is 180 degrees rotatedfrom the position in FIG. 52 , the chain 138 downshifts from thesprocket teeth 160 of the big chain ring 152 to the small chain ring 154as shown in FIG. 59 . More specifically, as the second downshift element212 b rises into contact with the chain 138, the angled contact face 338on the second downshift element blocks the chain from engaging thesprocket teeth 160 on the big chain ring 152. Instead, the angledcontact face 338 forces the chain 138 to redirect or deflect out ofalignment with the plane B of the big chain ring in the inboarddirection toward the plane S of the small chain ring 154. As the ridercontinues to pedal the front shift unit 150 in the rotation direction R,the chain 138 will continue to wrap around and engage the sprocket teeth162 of the small chain ring 154 as depicted in FIGS. 41 and 47 . Afterthe downshift operation is complete, the front shifting system in thisexample remains in the downshift state until the rider requests orexecutes an upshift, as described above.

In the disclosed example, the upshift element 210 is in the upshiftstate rotated to the position adjacent the big chain ring 152 whenexecuting an upshift operation and thereafter, until being moved for thenext downshift. At the same time, the downshift elements 212 a and 212 bare rotated to the position not overlapping the sprocket teeth 160 ofthe big chain ring 152. In this position, the downshift elements 212 aand 212 b are positioned so as not to engage the chain 138. Thisdownshift element position may be described as a neutral state, thoughthe system as a whole is in the upshift state. Likewise, the downshiftelements 212 a and 212 b in the downshift state are rotated to theposition overlapping the sprocket teeth 160 of the big chain ring 152when executing a downshift operation and thereafter, until being movedfor the next upshift. At the same time, the upshift element 210 isrotated to the position away from the big chain ring 152. In thisposition, the upshift element 210 is positioned so as not to engage thechain 138. This position may also be described as a neutral sate herein,though the system as a whole is in a downshift state.

As noted above, the front shift unit 150 in this example includes twodownshift elements 212 a and 212 b. The two downshift elements areoriented about 180 degrees opposite one another on the big chain ring152. Thus, the downshift elements provide two opportunities to executeor perform a downshift per each revolution of the crank assembly 132. Asa result, a downshift operation can be executed faster than if the frontshift unit 150 had only one downshift element. However, the frontshifting system can be provided in an alternate example with only onedownshifting element or can be provided with more than two downshiftingelements. In this example, the front shift unit 150 includes only oneupshift element 210, along with the two downshift elements 212 a and 212b. In an alternate example, the front shift unit may include a second ormore upshift elements as well. The front shifting system may include anynumber of upshift elements and/or downshift elements within the spritand scope of the disclosure. Increasing the number of upshift anddownshift elements will decrease the average time that it takes tocomplete a shift by placing a next available shift element that muchcloser to the upper working side of the chain when a shift is requestedor executed.

Referring to FIGS. 19-26 , a rider sometimes may pedal the crankassembly backwards opposite to the rotation direction R. In the eventthat the rider pedals backwards and while the upshift element 210 is inthe upshift state, the position and shape of the teeth 288 on the chainguiding pegs 280 and the position and shape of the hook 302 on the chainupshifting peg 282 can be configured and arranged to deflect or rejectthe chain 138. More specifically, the angled bottom surface 294 and thechamfered surfaces or chamfers 296 a, 296 b, and 296 c on the teeth 288and the angled bottom surface 306 and the chamfered surfaces or chamfers308 a, 308 b, 308 c on the hook 302 are configured so that the chain 138does not engage with the chain guiding pegs 280 or the chain upshiftingpeg 282. These angled surfaces and chamfers protect against a chainderailment that could occur if the chain 138 were to engage the chainguiding pegs 280 or the chain upshifting pegs while the rider ispedaling backwards. The angled bottom surface 294 and chamfers 296 a,296 b, and 296 c on the teeth 288 and the angled bottom surface 306 andchamfers 308 a, 308 b, and 308 c on the hook 302 may also function todeflect or reject the chain 138 when the chain guiding pegs 280 and thechain upshifting peg 282 cross over or rotate past the bottom or slackside of the chain after the upshift element 210 is biased or positionedin the upshift state, but before an upshift operation has occurred.

In another example, with reference to FIG. 61 , the front shiftingsystem may include an optional power meter 530 that is deployed andconfigured to measure the rider's power output while pedaling thebicycle 100. In this example, the power meter 530 is provided as a partof a modified front shift unit 532. The power meter 530 may includestrain measurement devices attached to the material of the chainringstructure between a torque input and output section so as to measurepower transmitted therethrough. The power meter 530 may include anindependent PCB including appropriate circuitry to determine, and/ortransmit signals indicative of, power transmitted through the chainringstructure. Electrical power to operate the power meter 530 may besupplied by the power supply 194 via a cable (not shown) extending fromthe power supply to the power meter. In another embodiment, the powermeter 530 and the front shift unit 532 may share PCB within the controlunit 184, rather than having a separate PCB for the power meter and thefront shift unit. In this embodiment strain measurement devices maystill be attached to the chainring structure and configured to measurestrain of the chainring structure.

In one example, the big chain ring 152 may have forty-eight (48)sprocket teeth 160 and the small chain ring 154 may have thirty-two (32)sprocket teeth 162. In such an example, both the number of sprocketteeth 160 on the big chain ring 152 and the number of sprocket teeth 162on the small chain ring 154 are multiples of four. Such an arrangementallows the downshift elements 212 a and 212 b to be positioned 180degrees offset or apart from each other around the circumference of thefront shift unit 150. Also, for each of the two downshift elementlocations, the spatial relationship or timing between the relevant teeth160 on the big chain ring 152 and the relevant teeth 162 on the smallchain ring 154 will be the same. In this way, the front shift unit 150can be designed such that the rotational timing between the big chainring and the small chain ring provides a high quality upshift componentgeometry and a high quality first downshift component geometry, whilealso assuring the second downshift component geometry will be identicalto the first downshift component geometry. Thus, in the disclosedexample, the number of teeth 160 on the big chain ring 152 and thenumber of teeth 162 on the small chain ring 154 are both multiples offour. However, the disclosed front shifting system and front shift unitare not limited to such a chain ring design. Any number of teeth can beprovided on either of the chain rings.

As described above, the position of the upshift element 210 isadjustable by manipulating the set screw 314. In the disclosed example,there is no device or mechanism disclosed to adjust the position of thedownshift elements 212 a and 212 b. However, a device or mechanismassociated with these elements may be included that allows adjustment.For example, the downshift element 212 a could be provided in two parts.One part may include the contact face 338 on the head 334 and a secondpart may include the cam surface 328 and the drive arm 326. Both of theparts may then be independently rotatable about the first downshiftshaft 496 a. A set screw may be threadably engaged with one of the twoparts and may have an exposed end in contact with the other of the twoparts. The set screw may then be used to adjust the position of thecontact face 338 of the head 334 relative to the cam surface 328 on thedrive arm 326. The specific construction of such an adjustable downshiftelement construction is not described further herein.

Referring to FIGS. 14, 15, 36, and 37 , some teeth 160 of the big chainring 152 and some teeth 162 of the small chain ring 154 may be providedhaving a special or different shape than other of the teeth. Forexample, two of the teeth 160 of the big chain ring 152 that immediatelyprecede the location of the downshift elements 212 a and 212 b may havean outboard face 540 with material that has been removed from theoutboard surface of the teeth. This tooth shape may be provided on thesetwo specific teeth 160 to allow the chain 138 to more easily deflectinboard during a downshift operation. In another example, one specifictooth 160 of the big chain ring 152 that immediately precedes theposition of the chain upshifting peg 282 and the hole 264 e may have aninboard face 542 with material that has been removed from the inboardsurface of the tooth. This tooth shape may be provided to allow thechain 138 to deflect or move slightly farther outboard before engagingthe hook 302 of the chain upshifting peg 282 during an upshiftingoperation. In another example, a series of the teeth 162 of the smallchain ring 154 are the first teeth to engage the chain 138 during adownshift operation. These teeth may have special chamfers 544 on thetooth surfaces to optimize chain management during a downshiftoperation. In still another example, a series of the teeth 160 of thebig chain ring 152 are the first teeth to engage the chain 138 after anupshift operation. These teeth may also have special chamfers 546 on thetooth surfaces to optimize chain management during an upshift operation.

In an alternate example, the front shifting system may be configured forwhat is termed “synchro shifting.” In synchro shifting, when a riderrequests or executes an upshift or a downshift, the front shiftingsystem automatically determines the combination of which front chainring, i.e., the big chain ring 152 or the small chain ring 154, andwhich sprocket of the rear cassette 140 should engage the chain 138. Thefront shifting system and rear derailleur then shift the chain to thedesired front chain ring and rear sprocket accordingly. The “synchroshift” system can be configured to shift through every available gearcombination in sequence, from the highest gear to the lowest gear, andvice versa.

In another alternate example, the front shifting system, and the rearshifting system as well, can be configured for automatic shifting. In anautomatic shifting system, the bicycle can be configured with sensorsthat sense various drive train operational characteristics, which areused to shift gears automatically. Any one or more of the sensedoperational characteristics may be sensed and used to determine when thesystem should shift gears. For example, such operational characteristicscan include pedaling torque, pedaling cadence, speed, and changes insuch characteristics over time. The front shifting system and rearshifting system can be configured to automatically shift gears on thebicycle, without direct input from the rider, when a predeterminedcombination of one or more of these characteristics is sensed ordetermined.

In another alternate example, the front shifting system, as well as therear shifting system, can be configured as what is known as a half-stepsystem. Half-step shifting is a known shifting technique where the gearratio change between successive rear sprockets is approximately doublethe gear ratio change between the front chain rings. When shifting thechain either up or down on the sprockets of the rear cassette, thehalf-step system can shift the chain on the front chain ring componentbetween the front chain rings during every shift and can shift the chainbetween the rear sprockets every other shift. In this type of half-stepsystem, very small, sequential gear ratio changes can be achieved.

The disclosed front shifting system and front shift unit 150 is atwo-state system. The disclosed two state system has only two states,which include a downshift state and an upshift state. In the downshiftstate, the parts or components are arranged to downshift the chain froma big chain ring to a smaller chain ring and then remain in that stateuntil asked to execute an upshift operation. In the upshift state, theparts or components are arranged to upshift the chain from a small chainring to a bigger chain ring and then remain in that state until asked toexecute a downshift operation. In an alternate example, the frontshifting system and the front shift unit may be configured as havingthree states. The three states can include an upshifting state, adownshifting state, and a different, neutral state for the upshiftingand downshifting elements. The parts or components can be arranged inthe upshifting state only when executing an upshift of the chain and canbe arranged in the downshifting state only when executing a downshift ofthe chain. The part or components can be configured to return to and bearranged in a neutral state when not executing an upshift or a downshiftof the chain. In other words, the front shifting system can be in theneutral state when neither the upshift element or elements nor thedownshift element or elements are engaged or arranged to upshift ordownshift, respectively, the chain. The parts or components of the frontshifting system and front shift unit 150 can thus be configured to be inthe neutral state when the rider is riding the bicycle and no shiftingoccurs.

In another alternate example, the gearmotor unit 200 and the electroniccontrol unit 184 may be contained or housed within the same housing orenclosure, rather than having separate housings, as in theabove-described example. The gearmotor unit and electronic control unitcan be provided as a single controller, which provides the functions ofboth the gearmotor unit and the electronic control unit.

In one example, the big chain ring 152 and the small chain ring 154 maybe integrally formed as one single part or chain ring component 228, asin the disclosed example. In an alternate example, the big chain ringand the small chain ring may instead be separately formed componentsthat are then either directly fixed to one another to form the chainring component indirectly joined to one another via a third component,such as a chain ring hub.

In one example, the various shifting mechanisms, parts, or components ofthe front shift unit 150 are all directly mounted to the chain ringcomponent. In the disclosed example, virtually all of the shiftingmechanisms, parts, or components are formed as an integrated part of, ormounted to, the big chain ring 152. In an alternate example, one, morethan one, or all of the various shifting mechanisms, parts, orcomponents may be formed as an integrated part of, or mounted to, thesmall chain ring 154. In yet another alternate example, one, more thanone, or all of the various shifting mechanism, parts, or components ofthe front shifting system and front shift unit may be mounted to adifferent, separate part (not shown) of the unit. That separate part maythen in turn be mounted to the front shift unit. For example, one, morethan one, or all of the various shifting mechanisms, parts, andcomponents may be mounted to the cowling of the front shift unit.

It is well known in the bicycle field that, during a pedal stroke, thetorque that a rider inputs to the crank assembly 132 varies as afunction of the angular position of the crank arms 134. In the disclosedexample, the crank arms 134 of the crank assembly 132 are angularlypositioned relative to the upshift element 210 and the downshiftelements 212 a and 212 b such that the pedal torque input by the rideris not near a maximum torque during an upshift operation or a downshiftoperation. In an alternate example, the crank arms 134 of the crankassembly 132 may be located at a different angular position relative tothe position of the upshift element 210 and the downshift elements 212 aand 212 b.

Specific materials are disclosed above for some of the shiftingmechanisms, parts, or components. The disclosed front shifting systemand front shift unit 150 is not limited to only those specificmaterials, or to any specific materials for any of the mechanisms,parts, or components. Other suitable materials may certainly beutilized. In just one alternate example, the upshift element 210 may bemade from an injection molded nylon material or a long fiber reinforcedthermoplastic material. In another example, the chain guiding pegs 280and the chain upshifting peg 282 may insert molded in place on the body270 of the upshift element 210. This would eliminate the need forindividually adjusting the position of each peg relative to the plane Cof the contact surfaces 276 on the body 270. Other such modificationsmay certainly be made to the upshift element and to other of the variousshifting mechanisms, parts, or components as well.

In another alternate example, the front shift unit 150 may be configuredto include additional sensors, such as a three-axis gyroscope and/or athree-axis accelerometer. Such components may be disposed on the PCB ofthe electronic control unit 184 or on another suitable part of the frontshift unit. These additional sensors may be employed to determine theangular position and/or the angular velocity of the front shift unit 150during pedaling. Such positional and velocity information may be used toimprove performance of the front shifting system, as discussed in moredetail below. Other types of additional sensors may also be used toobtain additional data and information, as desired.

In one example, the front shifting system, as well as the rear shiftingsystem, may be configured to disallow or prohibit shifting of the gearswhen a rider is not pedaling the bicycle 100 forward or, in other words,when the angular velocity of the front shift unit 150 is not greaterthan zero in the rotation direction R. The front shifting system, aswell as the rea shifting system, may alternatively be configured todisallow or prohibit shifting when the rider is not pedaling the bicyclefaster than a predetermined threshold value or, in other words, when theangular velocity of the front shift unit 150 is not greater than thepredetermined threshold value. This feature may be added to aid inpreventing a chain derailment or other undesired system behavior.

In another example, the front shifting system, as well as the rearshifting system, may be configured to abort a shift that is in progressif a rider pedals backwards during a shifting operation. If the riderpedals backwards during the execution of a shift, the front shiftingsystem, as well as the rear shifting system, may revert to the previousstate, prior to the beginning the shift, rather than continue theshifting operation. This feature may also be added to aid in preventinga chain derailment or other undesired system behavior.

In another example, the front shifting system, as well as the rearshifting system, may be configured to delay shifting until a desiredangular position of the front shift unit 150 has been achieved. Thisfeature can be achieved by employing one or more sensors to obtain twoaxes of accelerometer data. The collected data can be used to determinethe near real time angular position of the front shift unit 150 relativeto the gravity vector. For example, a sensor, such as an accelerometer,may be mounted to the bicycle frame 102 and may be used to determine theorientation of the bicycle 100 relative to the gravity vector. Theorientation of the front shift unit 150 relative to the bicycle 100 canthen be determined. Shifting of the front shift unit 150 can be delayeduntil a desired angular position of the front shift unit has beenachieved. The frame-mounted sensor may be eliminated if the errorsassociated with its absence are small.

In another example, the front shifting system may be configured to movethe upshift element 210 and/or the downshift elements 212 a and 212 b toan intermediate position until a shift is completed. After the shift iscompleted, the upshift element 210 and the downshift elements 212 a and212 b can be moved to a final, steady-state position. In one example,this feature may be used to optimize the positions of the upshiftelement 210 and/or the downshift elements 212 a and 212 b based on aposition of the rear sprocket or cog of the rear cassette 140 that isengaged with the chain 138, i.e. based on the chain line or chain angle.

FIGS. 62-74 show an embodiment in which the power supply, PCB, motor,shift mechanism and associated parts are attached to and supported by amechanism support bracket 661, rather than being directly attached toand supported by a chain ring component 655. The power supply, PCB,motor, shift mechanism and associated parts, together with the mechanismsupport bracket 661 are included in a mechanism module 660 that attachesto the chain ring in a way that will be described further herein. Afirst advantage of the embodiment is that it allows the mechanism moduleand chain ring component to be replaced independently of each other. Forexample, if the chain rings are worn, they can be easily replaced by theend user without replacing the mechanism module. A second advantage ofthe embodiment is that it may simplify and reduce the costs involved inthe manufacture of the chain ring component. A third advantage of theembodiment is that the housing of the mechanism module covers themechanism, protecting it from dirt and debris. A fourth advantage of theembodiment is that it may improve aerodynamics without the need of aseparate cowling.

Referring to FIGS. 62 and 63 , mechanism module 660 attaches to frontshifting unit 650 with a plurality of fasteners, for example five screws662 that thread into corresponding threaded holes in front shifting unit650. Other attachment techniques may be used. For example, rivets orother fasteners may be used to attach corresponding features of theparts.

FIGS. 63-66 show the mechanism module 660, and FIGS. 67-69 show themechanism support bracket 661 of mechanism module 660. Referring toFIGS. 67-69 , mechanism support bracket 661 has a plurality of holes672, five in this embodiment, configured to receive the aforementionedplurality of screws to attach mechanism module 660 to front shiftingunit 650.

Referring to FIGS. 67 and 69 , shafts 630, 631, 632, 633 are located inand supported by corresponding holes in mechanism support bracket 661,and perform the same functions as shafts 460, 496 a, 496 b, 506 ofprevious embodiments. Referring to FIG. 65 , gearmotor unit 200 isscrewed to mechanism support bracket 661 with two screws 186 that arethreaded into threads in mechanism support bracket 661. First and seconddownshift elements 612 a, 612 b are pivotably received on and supportedby first and second downshift pivot shafts 631, 633, respectively. Firstand second downshift element biasing springs 623, 624 are received onand supported by first and second downshift pivot shafts 631, 633,respectively. First legs of first and second downshift element biasingsprings 623, 624 engage first and second downshift elements 612 a, 612b, respectively, and second legs of first and second downshift elementbiasing springs 623, 624 engage mechanism support bracket 661. First andsecond downshift element biasing springs 623, 624 bias first and seconddownshift elements 612 a, 612 b in the same way as in previousembodiments.

Referring to FIGS. 70-72 upshift element 603 may be made of long fiberreinforced thermoplastic (“LFRT”), glass-filled nylon, or otherappropriate materials such as some metallic materials, and chain guidingelements 604 and chain upshifting element 605 may be made of hardenedsteel or other material operable to carry the appropriate chainupshifting and/or guiding loads and that may provide appropriate chaininteraction and wear characteristics. Chain guiding elements 604 andchain upshifting element 605 are preferably insert molded into upshiftelement 603. Thus, upshift element 603, chain guiding elements 604 andchain upshifting element 605 all may behave as one unitary member. Inother embodiments, the upshift elements and/or chain guiding elementsmay operate independently. Stop surfaces 674 project from upshiftelement 603 and stop against front shifting unit 650 when upshiftelement 603 is in the upshift position, preventing further rotation ofupshift element 603.

Referring to FIG. 65 , upshift element 603 is pivotably received on andsupported by first cam shaft 630. Upshift element biasing spring 622 isalso received on and supported by first cam shaft 630. A first leg ofupshift element biasing spring 622 engages upshift element 603, and asecond leg of upshift element biasing spring 622 engages mechanismsupport bracket 661. Upshift element biasing spring 622 biases upshiftelement 603 in the same way as in previous embodiments.

The remaining parts associated with the mechanism (cams, drive elements,springs, links, hub, etc.) may be supported and attached as described inprevious embodiments.

Referring to FIG. 64 , power supply latch 196 is pivotably attached toan axle fixed to mechanism support bracket 661. Printed circuit board(or PCB, see FIG. 63 ) 626 is housed inside a waterproof chamber inmechanism support bracket 661. Button 676 of PCB 626 is accessiblethrough a hole in mechanism support bracket 661, and LED 192 of PCB 626is visible through a clear lens in mechanism support bracket 661.Electrically conductive pogo pins of PCB 626 protrude from holes inmechanism support bracket 661, and electrically connect to terminals ofpower supply 194, which is attachable to (and removable from) mechanismmodule 660 by operation of latch 196. Wires (not shown) carry electricalpower and signals from PCB 626 to gearmotor unit 200.

Referring to FIGS. 73 and 74 , front shifting unit 650 has a pluralityof holes 678, which may be the five threaded holes described in thisexample, that receive the aforementioned fasteners (e.g. the fivescrews) that attach mechanism module 660 to front shifting unit 650.Machining of the front shifting unit 650 is simplified compared to otherembodiments, since difficult-to-machine cross-drilled holes of otherembodiments are omitted, and are replaced with threaded holes 678 whichare machined from the same direction as other features in front shiftingunit 650. Further, the omission of the bosses on which the cross-drilledholes were located results in a machining “blank” that is thinner,greatly reducing the amount of material that must be removed during themachining operation.

Referring to FIGS. 69 and 74 , mechanism support bracket 661 has twosurfaces 680, 682 that engage and abut corresponding surfaces 684, 621in front shifting unit 650 to transfer chain loads from the chain tofront shifting unit 650 as follows. During an upshift operation, thechain load is carried by chain guiding elements 604 and chain upshiftingelement 605. The chain load is transferred through chain guidingelements 604 and chain upshifting element 605, through upshift element603, through first cam shaft 630, through mechanism support bracket 661,through surfaces 680, 682 of mechanism support bracket 661, to surfaces684, 621 of front shifting unit 650. In this manner, screws 662 are notrequired to carry the chain load during an upshift operation.

FIG. 75 shows an alternate embodiment in which removable power supply194 is omitted, and instead, non-removable power supply 663 ispermanently installed inside mechanism module 660. Non-removable powersupply 663 performs the same function as removable power supply 194, andpreferably includes circuitry and structure providing the power supply663 as rechargeable. Non-removable power supply 663 is electricallyconnected to PCB 626.

FIG. 76 shows an alternate embodiment in which power supply 194 is againomitted, and power supply 664 is received inside the hollow space formedinside spindle 665. Power supply 664 is preferably connected byconductive cables and/or wires (not shown) to PCB 626. Power supply 664performs the same function as power supply 194, and is preferablyrechargeable. Power supply 664 may be removable, or may be permanentlyinstalled.

FIG. 77 shows a power meter 530 that is incorporated into all of theseembodiments. The power meter embodiment shown is well known in the art,and uses strain gauges that are attached to front shifting unit 650 inorder to measure the rider's torque output. The power meter 530 also mayinclude sensors to measure the rider's cadence. Using this torque andcadence data, the power meter 530 calculates the power output of therider. The power meter 530 may receive electrical power from the samebatteries 194, 663, and/or 664 that power the shift mechanism, or thepower meter may receive electrical power from a separate power meterpower supply 686 as shown in FIG. 77 . The power meter 530 may becovered by a waterproof cover (cover removed in FIG. 77 for clarity).

As previously indicated, and as will be discussed with reference to FIG.5B, exchanging, or shifting, a chain between two or more sprockets 152,154 may be accomplished with at least one (“1”) shift element 288 beingmoved into a chainline of a drive system. Shift elements 288, 302 arechain engaging elements such as pegs, hooks, or other elements asdescribed herein. Shift elements are configured to engage a link orplate of a chain. In the described embodiments, a single shift elementengages a singular link or link plate. The shift elements may beprotruding shift elements that move in an axial direction relative to arotational axis R of the sprockets. The protruding shift elements may beconfigured to extend and/or retract in the axial direction for movinginto and/or out of the chainline to engage the chain. The at least onemoving shift element may be disposed radially between a root circle R3of a larger sprocket and a tooth tip circle of a smaller sprocket R2.The at least one moving shift element may include an array or pluralityof protruding shift elements. In FIG. 5B the plurality of protrudingshift elements 288 are designated individually as 288A, 288B, 288C, 288Ddesignating different orientations on the chainring structure.

The protruding shift elements 288A 288B, 288C, 288D, 302 of the arraymay be disposed at different radial distances D1, D2, D3, D4, D5 from arotational axis R of the structure. These distances may also bedifferent relative to the larger and/or smaller sprockets. Asillustrated, a first protruding shift element 288A may be disposedbetween a root circle R1 and a tooth tip circle R2 of the smallersprocket 154. A second protruding shift element 302 may be disposedbetween the root circle and the tooth tip circle R4 of the largersprocket 152. A plurality of protruding shift elements 288B, 288C, 288Dmay be disposed radially and/or circumferentially between the firstprotruding shift element 288A and the second protruding shift element302. The plurality of protruding shift elements may have each have a tipconfigured to engage the chain. The respective tips each disposed atdifferent axial distances relative to the larger and smaller chain rings152, 154.

The plurality of protruding shift elements may cause the chain to beshifted through a transition zone T between the smaller chain ring teethand the larger chain ring teeth. For example, the transition zone may bedefined as the radial area between the tooth tip circle R2 and thelarger chain ring root circle R3. A plurality of protruding shiftelements 288B, 288C, 288D may be disposed in the transition zone T.

Exchanging, or shifting, a change between two or more sprockets may beaccomplished from a larger sprocket 152 to a smaller sprocket 154 usingdownshifting element, which may be formed as a slide or slanted planarsurface that may be moved into, and/or out of, the chainline at thelarger sprocket to cause the chain to slide or shift towards the smallersprocket. The downshifting elements may be disposed outside of thetransition zone T, but cause the chain to move through the transitionzone T.

In the disclosed examples, the front shift unit is generally describedas including the chain ring unit, including the big and small chainrings, and the front shift mechanism, including all of the various shiftcomponents. However, more or fewer of the parts and components of thebicycle may be included or considered as a part of the so-called frontshift unit within the scope of the present disclosure. Further, thefront shifting system is generally described herein as including thefront shift unit, the shifter, the chain, and the crank assemblycomponents. Again, more or fewer of the parts and components of thebicycle may be included or considered as a part of the so-called frontshifting system within the scope of present disclosure. In the disclosedexample, the drive wheel that is driven by the drive train is the rearwheel, though the disclosure is not limited thereto.

In one example, according to the teachings of the present disclosure, abicycle includes a frame, wheels for supporting the frame on a surface,a drive train operable to drive rotation of a drive wheel of the wheels,the drive train including a cassette carried adjacent the drive wheeland a chain coupled to the cassette. A front shifting assembly iscarried on the bicycle and includes a shifter operable to transmit awireless signal and a crank assembly having two crank arms and a pedalassociated with each of the two crank arms. The crank assembly isrotatable about a rotation axis. A front shift unit is coupled to thecrank assembly for rotation therewith about the rotation axis. The frontshift unit has a chain ring component and a shift mechanism coupled tothe chain ring component. The chain ring component has a big chain ringand a small chain ring. The small chain ring has a small diameter andthe big chain ring has a big diameter that is larger than the smalldiameter. The chain extends between the cassette and the chain ringcomponent. The shift mechanism is configured to receive the wirelesssignal from the shifter and to shift the chain between the big chainring and the small chain ring according to the wireless signal.

In one example, the shift mechanism can be on the big chain ring.

In one example, the shift mechanism can include at least one upshiftelement movable relative to the front shift unit to selectively engagethe chain to execute an upshift of the chain from the small chain ringto the big chain ring.

In one example, at least one upshift element of the shift mechanism canbe mounted to the big chain ring.

In one example, the shift mechanism can include at least one downshiftelement movable relative to the front shift unit to selectively engagethe chain to execute a downshift of the chain from the big chain ring tothe small chain ring.

In one example, at least one downshift element of the shift mechanismcan be mounted to the big chain ring.

In one example, the shift mechanism can include a first downshiftelement and a second downshift element. The second downshift element canbe positioned opposite or 180 degrees offset relative to the firstdownshift element around a circumference of the chain ring component.

In one example, the shift mechanism can include at least one downshiftelement movable relative to the chain ring component to selectivelyengage the chain to execute a downshift of the chain from the big chainring to the small chain ring.

In one example according to the teachings of the present disclosure, afront shift unit for a bicycle includes a chain ring component having abig chain ring and a small chain ring joined for co-rotation with oneanother about a rotation axis. The big chain ring has a big diameter anda plurality of big ring sprocket teeth and the small chain ring has asmall diameter and a plurality of small ring sprocket teeth. The bigdiameter is larger than the small diameter. The front shift unit alsoincludes a shift mechanism coupled to the chain ring component. Theshift mechanism includes an electronic control unit, a gearmotor unit,at least one upshift element, at least one downshift element, and apower supply. The power supply is arranged to provide power for theelectronic control unit and the gearmotor unit to operate the at leastone upshift element and the at least one downshift element. According toa wireless upshift signal, the at least one upshift element is operableby the electronic control unit and the gearmotor unit to shift a chainfrom the plurality of small ring sprocket teeth on the small chain ringto the plurality of big ring sprocket teeth on the big chain ring.According to a wireless downshift signal, the at least one downshiftelement is operable by the electronic control unit and the gearmotorunit to shift a chain from the plurality of big ring sprocket teeth onthe big chain ring to the plurality of small ring sprocket teeth on thesmall chain ring.

In one example, the chain ring component can be formed as one integratedcomponent from the same material.

In one example, each of the electronic control unit, the gearmotor unit,the at least one upshift element, the at least one downshift element,and the power supply can be carried on the big chain ring of the chainring component.

In one example, each of the electronic control unit, the gearmotor unit,the at least one upshift element, the at least one downshift element,and the power supply can be carried on an outboard surface of the bigchain ring.

In one example, the at least one downshift element can include a firstdownshift element and a second downshift element positioned opposite thefirst downshift element around a circumference of the chain ringcomponent

In one example, a first downshift element of the shift mechanism and anupshift element of the shift mechanism can be operable by a first linkcoupled to the gearmotor unit.

In one example, the shift mechanism can include a first cam shaftcoupled to the gearmotor unit and rotatable about a first cam axis. Anupshift driver can be rotatable about the first cam axis and configuredto move an upshift element of the shift mechanism between an upshiftstate capable of engaging a chain on the small ring sprocket teeth ofthe small chain ring and a neutral state not capable of engaging a chainon the chain ring component. A first downshift driver can be rotatableabout the first cam axis and configured to move a first downshiftelement of the shift mechanism between a downshift state capable ofengaging a chain on the big ring sprocket teeth of the big chain ringand a neutral state not capable of engaging a chain on the chain ringcomponent.

In one example, when an upshift element of the shift mechanism moves toan upshift state to engage a chain, a first downshift element of theshift mechanism can be in a neutral state to not engage the chain. Whenthe first downshift element moves to a downshift state to engage thechain, the upshift element can be in a neutral state to not engage thechain.

In one example, the shift mechanism can include a second cam shaftcoupled to the gearmotor unit and rotatable about a second cam axis. Asecond downshift driver can be rotatable about the second cam axis andconfigured to move a second downshift element of the shift mechanismbetween a downshift state capable of engaging a chain on the big ringsprocket teeth of the big chain ring and a neutral state not capable ofengaging a chain on the chain ring component.

In one example, when an upshift element of the shift mechanism moves toan upshift state to engage a chain, a first downshift element and asecond downshift element of the shift mechanism can be in a neutralstate to not engage the chain. When the first and second downshiftelements move to a downshift state to engage the chain, the upshiftelement can be in the neutral state to not engage the chain.

In one example, a first downshift element and a second downshift elementof the shift mechanism can move in concert with one another between adownshift state and a neutral state.

In one example, a second downshift element of the shift mechanism can beoperable by a second link coupled to the gearmotor unit.

In one example according to the teachings of the present disclosure, afront shifting system for a bicycle includes a shifter mountable on thebicycle. The shifter is operable to transmit a wireless signal. Thefront shifting system includes a crank assembly having two crank armsand a pedal associated with each of the two crank arms. The crankassembly is rotatable about a rotation axis. The front shifting systemincludes a chain and a front shift unit coupled to the crank assemblyand rotatable about the rotation axis. The front shift unit includes achain ring component with a big chain ring and a small chain ring. Thesmall chain ring has a small diameter and the big chain ring has a bigdiameter that is larger than the small diameter. The front shift unitalso includes a shift mechanism coupled to and rotatable with the chainring component about the rotation axis. The shift mechanism isconfigured to receive the wireless signal from the shifter and to shiftthe chain between the big chain ring and the small chain ring accordingto the wireless signal.

In one example, the shifter can be mountable on a bicycle remote fromthe front shift unit.

In one example, the shift mechanism can include an electronic controlunit, a gearmotor unit in communication with the electronic controlunit, at least one upshift element coupled to the gearmotor unit, atleast one downshift element coupled to the gearmotor unit, and a powersupply arranged to provide power for the electronic control unit and thegearmotor unit to operate the at least one upshift element and the atleast one downshift element.

In one example, according to a wireless upshift signal received by theelectronic control unit, the at least one upshift element can beoperable by the gearmotor unit to shift the chain from the small chainring to the big chain ring. According to a wireless downshift signalreceived by the electronic control unit, the at least one downshiftelement can be operable by the gearmotor unit to shift the chain fromthe big chain ring to the small chain ring.

In one example, each of the electronic control unit, the gearmotor unit,the at least one upshift element, the at least one downshift element,and the power supply can be carried on the big chain ring of the chainring component.

In one example, at least one downshift element of the shift mechanismcan include a first downshift element and a second downshift element,which can be positioned opposite the first downshift element around acircumference of the chain ring component.

In one example, a first downshift element and an upshift element of theshift mechanism can be operable by a first link coupled to the gearmotorunit.

In one example, a second downshift element of the shift mechanism can beoperable by a second link coupled to the gearmotor unit.

In one example, the shift mechanism can include a first cam shaftcoupled to the gearmotor unit and rotatable about a first cam axis. Theshift mechanism can also include an upshift driver rotatable about thefirst cam axis and configured to move an upshift element of the shiftmechanism between an upshift state engaging the chain on the small chainring and a neutral state not engaging the chain on the chain ringcomponent. The shift mechanism can also include a first downshift driverrotatable about the first cam axis and configured to move a firstdownshift element of the shift mechanism between a downshift stateengaging the chain on the big chain ring and a neutral state notengaging the chain on the chain ring component.

In one example, when an upshift element of the shift mechanism moves toan upshift state, a first downshift element can be in a neutral state.When the first downshift element moves to a downshift state, the upshiftelement can be in the neutral state.

In one example, the shift mechanism can include a second cam shaftcoupled to the gearmotor unit and rotatable about a second cam axis. Theshift mechanism can also include a second downshift driver rotatableabout the second cam axis and configured to move a second downshiftelement of the shift mechanism between a downshift state engaging thechain on the big chain ring and a neutral state not engaging the chainon the chain ring component.

In one example, when an upshift element of the shift mechanism moves toan upshift state, a first downshift element and a second downshiftelement of the shift mechanism can be in a neutral state. When the firstand second downshift elements move to a downshift state, the upshiftelement can be in the neutral state.

In one example, first and second downshift elements of the shiftmechanism can move in concert with one another between a downshift stateand a neutral state.

In one example, the chain ring component can be formed as one integralstructure including the big chain ring and the small chain ring.

In one example according to the teachings of the present disclosure, amethod of mounting a front shift system on a bicycle includes mounting ashifter to a portion of the bicycle. The shifter is operable to transmita wireless signal. A crank assembly rotatable about a rotation axis isattached to a frame of the bicycle. The crank assembly has two crankarms, a pedal associated with each of the two crank arms, and a frontshift unit coupled to the crank assembly for rotation therewith aboutthe rotation axis. The front shift unit has a chain ring component and ashift mechanism carried by the chain ring component. A chain isconnected between the chain ring component and a rear cassette of thebicycle. The shifter is paired with an electronic control unit of theshift mechanism carried by the chain ring component.

In another example a bicycle front shifting assembly is presented. Thefront shifting assembly includes a front shift unit configured to becoupled to a crank assembly for rotation therewith about a rotationaxis, the front shift unit having a chain ring component and a shiftmechanism coupled to the chain ring component. The chain ring componenthas a big chain ring having a plurality of teeth defining a bigchainring plane and a small chain ring having a plurality of teethdefining a small chainring plane, the small chain ring having a smalldiameter and the big chain ring having a big diameter that is largerthan the small diameter. The shift mechanism includes at least oneprotruding shift element disposed in a transition zone between the bigchain ring and the small chain ring, the shift mechanism configured tomove the at least one protruding shift element axially between the bigchainring plane and the small chainring plane. The shift mechanism mayinclude a plurality of protruding shift elements disposed in thetransition zone. The plurality of protruding shift elements may beupshift elements. The shift mechanism may include an upshift elementconfigured to move axially to intersect the small chain ring plane. Theupshift element configured to move axially to intersect the small chainring plane may be disposed radially between a root circle and a toothtip circle of the small chain ring. The shift mechanism may furtherinclude at least one downshift element movable relative to the frontshift unit to selectively engage the chain to execute a downshift of achain from the big chain ring to the small chain ring. The at least onedownshift element may include a first downshift element and a seconddownshift element. The second downshift element may be positionedopposite the first downshift element around a circumference of the chainring component. The front shift unit may further comprise an electricmotor rotating fixed to the chain ring component, the electric motorconfigured to cause the at least one protruding shift element to moveaxially. The shift mechanism may further include at least one downshiftelement movable relative to the front shift unit to selectively engagethe chain to execute a downshift of a chain from the big chain ring tothe small chain ring, and the electric motor is configured to also causethe downshift element to move.

In another example, a front shift unit for a bicycle is provided. Thefront shift unit includes a chain ring component having a big chain ringand a small chain ring joined for co-rotation with one another about arotation axis, the big chain ring having a big diameter and a pluralityof big ring sprocket teeth and the small chain ring having a smalldiameter and a plurality of small ring sprocket teeth, the big diameterbeing larger than the small diameter. The front shift unit also includesa shift mechanism coupled to the chain ring component, the shiftmechanism including an electronic control unit, a gearmotor unit, atleast one upshift element, at least one downshift element, and a powersupply arranged to provide power for the electronic control unit and thegearmotor unit to operate the at least one upshift element and the atleast one downshift element. The at least one upshift element isdisposed in a transition zone between the small chain ring teeth and thebig chain ring teeth and axially movable by the electronic control unitand the gearmotor unit to shift a chain from the plurality of small ringsprocket teeth on the small chain ring to the plurality of big ringsprocket teeth on the big chain ring. The at least one downshift elementis operable by the electronic control unit and the gearmotor unit toshift a chain from the plurality of big ring sprocket teeth on the bigchain ring to the plurality of small ring sprocket teeth on the smallchain ring. The chain ring component may be formed as one integratedcomponent from the same material. The at least one upshift element mayinclude a plurality of upshift elements. Each of the electronic controlunit, the gearmotor unit, the at least one upshift element, the at leastone downshift element, and the power supply may be carried on anoutboard surface of the big chain ring. The at least one downshiftelement includes a first downshift element and a second downshiftelement positioned opposite the first downshift element around acircumference of the chain ring component. The first downshift elementand the upshift element may be operable by a first link coupled to thegearmotor unit.

The shift mechanism may further include a first cam shaft coupled to thegearmotor unit and rotatable about a first cam axis, an upshift driverrotatable about the first cam axis and configured to move the upshiftelement between an upshift state capable of engaging a chain on thesmall ring sprocket teeth of the small chain ring and a neutral statenot capable of engaging a chain on the chain ring component, and a firstdownshift driver rotatable about the first cam axis and configured tomove the first downshift element between a downshift state capable ofengaging a chain on the big ring sprocket teeth of the big chain ringand a neutral state not capable of engaging a chain on the chain ringcomponent. The upshift element may move to the upshift state, the firstdownshift element is in the neutral state, and wherein, when the firstdownshift element moves to the downshift state, the upshift element isin the neutral state. The shift mechanism may further include a secondcam shaft coupled to the gearmotor unit and rotatable about a second camaxis, and a second downshift driver rotatable about the second cam axisand configured to move the second downshift element between thedownshift state capable of engaging a chain on the big ring sprocketteeth of the big chain ring and the neutral state not capable ofengaging a chain on the chain ring component. The at least one upshiftelement may include a plurality of upshift elements and the plurality ofupshift elements move in concert with one another to achieve the upshiftstate.

Although certain front shifting system examples, front shift unitexamples, shifting mechanisms, parts, and/or components of same, andshifting methods have been described herein in accordance with theteachings of the present disclosure, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allembodiments of the teachings of the disclosure that fairly fall withinthe scope of permissible equivalents.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Additionally, the illustrations are merely representational and may notbe drawn to scale. Certain proportions within the illustrations may beexaggerated, while other proportions may be minimized. Accordingly, thedisclosure and the figures are to be regarded as illustrative ratherthan restrictive.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or variation of a sub-combination.

Similarly, while operations and/or acts are depicted in the drawings anddescribed herein in a particular order, this depiction should not beunderstood as requiring that such operations be performed in theparticular order shown or in sequential order, or that all illustratedoperations be performed, to achieve desirable results. In certaincircumstances, multitasking and parallel processing may be advantageous.Moreover, the separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, are apparent to those of skill in the artupon reviewing the description.

The Abstract of the Disclosure is provided with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, variousfeatures may be grouped together or described in a single embodiment forthe purpose of streamlining the disclosure. This disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, inventive subject matter may bedirected to fewer than all of the features of any of the disclosedembodiments. Thus, the following claims are incorporated into theDetailed Description, with each claim standing on its own as definingseparately claimed subject matter.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention. The claims should not be read as limited to thedescribed order or elements unless stated to that effect. Therefore, allembodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

What is claimed is:
 1. A front shifting system for a bicycle, the frontshifting system comprising: a shifter mountable on a bicycle, theshifter operable to transmit a wireless signal; a crank assemblyconfigured to include two crank arms and a pedal associated with each ofthe two crank arms, the crank assembly rotatable about a rotation axis;a chain; and a front shift unit coupled to the crank assembly androtatable about the rotation axis, the front shift unit including achain ring component with a big chain ring and a small chain ring, thesmall chain ring having a small diameter and the big chain ring having abig diameter that is larger than the small diameter, and a shiftmechanism coupled to and rotatable with the chain ring component aboutthe rotation axis, the shift mechanism configured to receive thewireless signal from the shifter and to shift the chain between the bigchain ring and the small chain ring according to the wireless signal. 2.The front shifting system of claim 1, the shifter being mountable on abicycle remote from the front shift unit.
 3. The front shifting systemof claim 1, wherein the shift mechanism includes an electronic controlunit, a gearmotor unit in communication with the electronic controlunit, at least one upshift element coupled to the gearmotor unit, atleast one downshift element coupled to the gearmotor unit, and a batteryarranged to provide power for the electronic control unit and thegearmotor unit to operate the at least one upshift element and the atleast one downshift element.
 4. The front shifting system of claim 3,wherein, according to a wireless upshift signal received by theelectronic control unit, the at least one upshift element is operable bythe gearmotor unit to shift the chain from the small chain ring to thebig chain ring, and wherein, according to a wireless downshift signalreceived by the electronic control unit, the at least one downshiftelement is operable by the gearmotor unit to shift the chain from thebig chain ring to the small chain ring.
 5. The front shifting system ofclaim 3, wherein each of the electronic control unit, the gearmotorunit, the at least one upshift element, the at least one downshiftelement, and the battery are carried on the big chain ring of the chainring component.
 6. The front shifting system of claim 3, wherein the atleast one downshift element includes a first downshift element and asecond downshift element positioned opposite the first downshift elementaround a circumference of the chain ring component.
 7. The frontshifting system of claim 6, wherein the first downshift element and theupshift element are operable by a first link coupled to the gearmotorunit.
 8. The front shift unit of claim 7, wherein the second downshiftelement is operable by a second link coupled to the gearmotor unit. 9.The front shifting system of claim 7, wherein the shift mechanismfurther comprises: a first cam shaft coupled to the gearmotor unit androtatable about a first cam axis; an upshift driver rotatable about thefirst cam axis and configured to move the upshift element between anupshift state engaging the chain on the small chain ring and a neutralstate not engaging the chain on the chain ring component; and a firstdownshift driver rotatable about the first cam axis and configured tomove the first downshift element between a downshift state engaging thechain on the big chain ring and a neutral state not engaging the chainon the chain ring component.
 10. The front shifting system of claim 9,wherein, when the upshift element moves to the upshift state, the firstdownshift element is in the neutral state, and wherein, when the firstdownshift element moves to the downshift state, the upshift element isin the neutral state.
 11. The front shifting system of claim 9, whereinthe shift mechanism further comprises: a second cam shaft coupled to thegearmotor unit and rotatable about a second cam axis; and a seconddownshift driver rotatable about the second cam axis and configured tomove the second downshift element between the downshift state engagingthe chain on the big chain ring and the neutral state not engaging thechain on the chain ring component.
 12. The front shifting system ofclaim 11, wherein, when the upshift element moves to the upshift state,the first and second downshift elements are in the neutral state, andwherein, when the first and second downshift elements move to thedownshift state, the upshift element is in the neutral state.
 13. Thefront shifting system of claim 11, wherein the first and seconddownshift elements move in concert with one another between thedownshift state and the neutral state.
 14. The front shifting system ofclaim 1, wherein the chain ring component is formed as one integralstructure including the big chain ring and the small chain ring.